240+ Science Words That Start With U: Full List With Meanings

Science words starting with U help students improve vocabulary in physics, earth science, biology, and technology. These terms also support better learning and topic understanding.

This article explains more than 240 science words that start with U, along with their meanings in simple tables. You will find words for physical science, earth science, life science, environmental science, and computer science. It also includes grade-wise vocabulary lists for kids, from 4th to 8th grade, to make studying easier and more organized.

Physical Science Words That Start With U

Word	Meaning
Ultraviolet	A type of light with shorter wavelength than visible light
Uniform Motion	Movement at a constant speed in a straight line
Uranium	A radioactive metal used in nuclear energy
Upthrust	The upward force exerted by a fluid on an object
Unbalanced Force	Forces that cause a change in motion
Ultrasound	High frequency sound waves above human hearing
Uplift	The rising of Earth’s crust due to geological forces
Universal Joint	A joint allowing rotation in different directions
Unit Cell	Smallest repeating part of a crystal structure
Undamped Motion	Motion that does not lose energy
Ultrafine Particles	Very tiny particles in the atmosphere
Ultrasonic Speed	Speed faster than sound in air
Uncertainty Principle	Physics rule that some things cannot be measured exactly at the same time
Underpressure	Pressure lower than normal surroundings
Utility Energy	Useful energy after energy conversion
Uranography	Study of the heavens and celestial objects
Upwelling	Movement of deep water to the surface
Uptake	Absorption of molecules into a material
Urethane Resin	Material used in engineering and construction
Ultrafilter	A fine filter for separating small particles

Earth Science Words That Start With U

Word	Meaning
Uplift	Rising of land due to tectonic forces
Upper Mantle	Layer of Earth below the crust
Urbanization	Growth of cities affecting land and nature
Ultrabasic Rocks	Igneous rocks low in silica
Undercut	Erosion at the base of a slope or cliff
Unconformity	A gap in the rock record
Underground Water	Water stored below Earth’s surface
U-shaped Valley	Valley formed by glaciers
Upstream	Direction opposite the flow of a river
Urea Cycle	Nitrogen removal process affecting soil chemistry
Undersea Ridge	Mountain chain under the ocean
Uplift Rate	Speed of land elevation change
Unconsolidated Sediments	Loose particles not cemented into rock
Upwelling Zone	Area where nutrient-rich water rises
Ultraborehole	Very deep drilling hole in Earth’s crust
Uraninite	Mineral rich in uranium
Undulation	Wave-like bending of rock layers
Ultramafic Magma	Magma high in magnesium and iron
UTM Coordinates	Grid mapping system used in geography
Underflow	Water flowing beneath a riverbed

Life Science Words That Start With U

Word	Meaning
Ulna	Bone in the forearm
Uterus	Organ where fetus develops
Urea	Waste chemical removed by kidneys
Urine	Liquid waste made by kidneys
Unicellular	Organism made of one cell
Upregulation	Increase in cell activity or gene expression
Umbilical Cord	Structure connecting fetus to placenta
Uracil	One of the bases of RNA
Urticaria	Skin condition causing itching and hives
Ulcer	Open sore on tissue
Ubiquitous	Found everywhere in cells
Urochordata	Group of simple marine animals
Uropod	Tail part of crustaceans
Urodela	Amphibians like salamanders
Uvea	Part of the eye supplying blood
Urethra	Tube that carries urine outside the body
Ultrastructure	Fine structure of cells seen under EM
Urinary System	Body system removing waste
Ubiquitin	Protein marking damaged proteins
Uptake	Absorption by cells

Environmental Science Words That Start With U

Word	Meaning
Upcycling	Reusing waste into useful products
Urban Ecology	Study of nature in city environments
Ultraviolet Index	Measure of UV radiation danger
Unsustainable	Using resources faster than replacement
Upstream Pollution	Pollution entering water from above flow
Urban Heat Island	City heat increase compared to countryside
Untreated Waste	Waste released without cleaning
Understory	Vegetation layer under tree canopy
Upland	Elevated land area
Uranium Mining	Extraction of radioactive mineral
Utility Planning	Managing energy and public services
Unleaded Fuel	Fuel without lead pollutants
Unrenewable	Resource that cannot be replaced quickly
Underwater Habitat	Living environment below water
Upwelling	Cold water rising bringing nutrients
Unregulated Emissions	Pollution released without control
Urea Fertilizer	Nitrogen fertilizer used in farming
Umbrella Species	Species that help protect many others
Urban Forestry	Planting and care of city trees
Unit Pricing	Environmental economics pricing system

Computer Science Words That Start With U

Word	Meaning
URL	Address of a webpage
USB	Universal serial bus connector
User Interface	Interaction screen between device and user
Upload	Send data to the internet
Update	Improve software or system
Unicode	Standard system for text characters
Username	Identity used to log into systems
UI Design	Designing user-friendly screens
Uninstall	Remove software from computer
Utility Program	Tool software for system tasks
Unix	Operating system used for servers
Uptime	Time system remains running
Undo	Reverse last action
Unit Testing	Testing smallest parts of code
UML	Unified Modeling Language for software design
UART	Serial communication hardware
Unsupervised Learning	Machine learning without labeled data
URL Encoding	Encoding text inside web addresses
UDF	File system standard
UPS	Power backup system for computers

Science Words That Start With U With Meaning

Word	Meaning
Universe	All matter and space
Uranus	Planet in outer solar system
Ultraviolet	High energy invisible light
Upthrust	Upward force in fluids
Unbalanced Force	Force that causes movement
Uranium	Heavy radioactive element
Uvula	Small part hanging in throat
Upwelling	Rising of deep ocean water
Unicellular	Single-celled organism
Uplift	Raising of land by Earth forces
Uncertainty Principle	Limit of measuring quantum particles
Ultrasound	High frequency sound waves
Urinary Tract	Organs producing and removing urine
Urbanization	Change of land due to city growth
Universal Joint	Joint with rotating flexibility
Uptake	Absorption by organisms
Ulcer	Tissue sore
Unit Cell	Basic crystal structure
Undercut	Erosion at base of cliffs
Umbilical Cord	Connects fetus and mother

Science Words That Start With U For Kids

Word	Meaning
Universe	Everything in space
Uranus	A big cold planet
Ultraviolet	Invisible sunlight that can burn skin
Upthrust	Push from water that keeps things afloat
Urine	Pee made by the body
Ulna	Arm bone
Uterus	Where a baby grows inside mom
Umbrella Bird	A bird with a special head shape
Underwater	Below the surface of water
Upstream	Toward where a river starts
Upcycle	Make something useful from old things
Updraft	Warm air going up
Unicornfish	Fish with a horn-like structure
Undersea	Below the ocean
Uplift	Land rising up
Urchin (Sea Urchin)	Small spiky animal in the sea
Upland	High land area
Uracil	Part of RNA in cells
Urethane	A safe plastic material
Urea	Waste removed from the body

Science Words That Start With U 4th Grade

Word	Meaning
Universe	All stars, planets, and galaxies
Uranus	A planet that spins on its side
Ultraviolet Light	Invisible rays from the sun
Updraft	Air moving upward
Upthrust	Water pushing objects upward
Unicellular	One cell organism
Urbanization	More buildings and roads in land
Undersea	Deep below the sea
Uplift	Earth’s crust rising
Uranium	A metal used for nuclear power
Uvula	Small soft tissue in the throat
Ulna	One of our arm bones
Urea	Body waste
Uptake	Absorbing nutrients or water
Ultrasound	Sound waves too high to hear
Umbilical Cord	Connects baby to mother inside womb
Undercut	Erosion at bottom of cliffs
Upcycle	Reusing waste creatively
Universal Joint	Joint allowing rotation
Urban Heat Island	Cities get hotter than villages

Science Words That Start With U 5th Grade

Word	Meaning
Universe	Everything that exists
Upwelling	Deep water rising to ocean surface
Urban Ecology	Nature inside cities
Uranium	Radioactive energy source
Ultrastructure	Tiny cell features
Ultraviolet Index	Risk level of sun radiation
Unicellular	Single cell life
Uterus	Organ for baby development
Uptake	Absorption of nutrients
Umbra	Darkest part of a shadow
U-shape Valley	Valley made by glaciers
Upstream	Toward river source
Unit Cell	Basic crystal pattern
Understory	Plants under trees in forests
Underflow	Water moving under riverbeds
Ultrasonic Speed	Faster than sound
Urban Forestry	Caring for city trees
Ultra Filter	Very fine filter
Ultramafic	Rock rich in iron and magnesium
Unbalanced Force	Force that causes motion change

Science Words That Start With U 6th Grade

Word	Meaning
Urbanization	Building cities changes land
Uplift	Movement of Earth’s crust upward
Unconformity	Gaps in rock records
Unrenewable Resource	Cannot be replaced quickly
Ultraviolet Radiation	High energy sunlight
Unsupervised Learning	Machine learning type
Ultrasound Imaging	Medical scan using sound waves
Uranography	Mapping the skies
Urea Cycle	Waste removal in organisms
Ubiquitous	Found everywhere in cells
Upwelling Zone	Nutrient-rich water rises
Undulation	Wavelike bending in rocks
Unit Testing	Testing small code parts
Ultramafic Magma	Iron-rich molten rock
Umbrella Species	Protects entire ecosystems
Underwater Habitat	Living space under oceans
Ultrafiltration	Filtering tiny particles
Upstream Pollution	Pollution from river source
Unbalanced Charge	Electric charges not equal
Utility Program	Small helpful computer tool

Science Words That Start With U 7th Grade

Word	Meaning
Universal Solvent	Water dissolving many substances
Ultra High Frequency	Radio wave range
Urea	Nitrogen waste in urine
Universal Law of Gravitation	Gravity pulls objects together
Ultrasound Therapy	Healing using sound waves
Ultrafine Dust	Tiny harmful particles in air
Urban Heat Island Effect	Warm cities due to buildings
Unicellular Organism	Organism of one cell
Updraft Cloud Formation	Rising air creates clouds
Uranium Decay	Radioactive breakdown
Urea Fertilizer	Nitrogen source for crops
Urochrome	Pigment in urine
Ultra Clean Air	Air with very low pollution
Underwater Volcano	Volcano below the sea
Ubiquitin System	Removes damaged proteins
Undercut Erosion	Riverbank erosion
Uncertainty Principle	Limits of physics measurement
Uptake Kinetics	Rate of absorption
Urban Pollution	Pollution from city life
Ultrastructure Study	Electron microscope cell study

Science Words That Start With U 8th Grade

Word	Meaning
Universal Set	All possible elements in a set
Urey-Miller Experiment	Study on origin of life
Ultraviolet Absorption	Energy taken in by molecules
Uranium Isotopes	Different forms of uranium
Ungulate	Hoofed animal
Unicellular Eukaryote	Single cell with nucleus
Unsupervised Algorithm	AI learning without labels
Upthrust Force	Buoyant force in fluids
Ubiquitin Protein	Marks proteins for recycling
Ultracentrifuge	Machine that spins at high speed
Urogenital System	Organs for waste and reproduction
Uremia	Kidney failure toxic buildup
Ultrasonic Sensors	Detect objects using sound
Uplift Zones	Areas with rising crust
Urban Sustainability	Eco-friendly city planning
Umbilical Vessels	Blood vessels in cord
Ultrastructure Analysis	Sub-cellular study
Uranology	Study of planets
Unstable Isotope	Atom breaking down for stability
Undersaturated Solution	Can dissolve more solute

Final Thoughts

Learning new science words that start with U helps students grow their knowledge in many subjects. These terms make homework easier, improve writing and boost confidence in class. Keep practicing and using these words in daily learning to remember them better.

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