Meaning: Cloudy or opaque, often due to stirred-up sediment.

Part of speech: adjective

Example: The river was turbid after the heavy rain.

Category: Science › Chemistry

Synonyms:

• cloudy
• muddy

Antonyms:

• clear
• transparent

Meaning: Irregular motion of air or fluid, often causing discomfort.

Part of speech: noun

Example: The flight experienced turbulence during the storm.

Category: Science › Physics

Synonyms:

• roughness
• instability

Antonyms:

• calm
• stability

Meaning: The study or classification of types.

Part of speech: noun

Example: The typology of plants helps in understanding biodiversity.

Category: Science › Biology

Synonyms: classification

Meaning: A large carnivorous dinosaur of the genus Tyrannosaurus.

Part of speech: noun

Example: The tyrannosaur was one of the largest predators of its time.

Category: Science › Paleontology

Synonyms: Tyrannosaurus rex

Meaning: an unidentified flying object

Part of speech: noun

Example: Many people believe UFOs are evidence of extraterrestrial life.

Category: Science › Astronomy

Synonyms: flying saucer

Meaning: the study of UFOs

Part of speech: noun

Example: Ufology is a popular subject among enthusiasts.

Category: Science › Astronomy

Meaning: having a frequency above the range of human hearing

Part of speech: adjective

Example: Ultrasonic waves are used in medical imaging.

Category: Science › Physics

Synonyms: high-frequency

Meaning: having a wavelength shorter than visible light

Part of speech: adjective

Example: Ultraviolet rays can cause sunburn.

Category: Science › Physics

Synonyms: UV

Meaning: the fully shaded inner region of a shadow

Part of speech: noun

Example: The umbra of the eclipse was visible from the city.

Category: Science › Physics

Synonyms: shadow

Meaning: Not modified or changed to fit a particular condition.

Part of speech: adjective

Example: The unadjusted figures do not reflect the recent changes.

Category: Science

Synonyms:

• unaltered
• unchanged

Antonyms:

• adjusted
• modified

Meaning: Pure; not mixed with anything else.

Part of speech: adjective

Example: He felt unalloyed joy at the news.

Category: Science

Synonyms:

• pure
• unmixed

Antonyms:

• alloyed
• mixed

Meaning: Not expected or predicted.

Part of speech: adjective

Example: The unanticipated results surprised the researchers.

Category: Science

Synonyms:

• unexpected
• unforeseen

Antonyms:

• anticipated
• expected

Meaning: To disturb the stability or equilibrium of something.

Part of speech: verb

Example: The sudden noise unbalanced the cat.

Category: Science

Synonyms:

• disturb
• upset

Antonyms:

• balance
• stabilize

Meaning: Not in a state of equilibrium; unstable.

Part of speech: adjective

Example: The unbalanced load caused the truck to tip.

Category: Science

Synonyms:

• unstable
• uneven

Antonyms:

• balanced
• stable

Meaning: Fair and impartial; not biased.

Part of speech: adjective

Example: The report was written in an unbiased manner.

Category: Science › Research

Synonyms:

• impartial
• neutral

Antonyms:

• biased
• partial

Meaning: Not stopping; continuous.

Part of speech: adjective

Example: The unceasing noise made it hard to concentrate.

Category: Science › Physics

Synonyms:

• constant
• relentless

Antonyms:

• ceasing
• stopping

Meaning: Not disputed or questioned.

Part of speech: adjective

Example: The theory remained unchallenged for decades.

Category: Science

Synonyms:

• undisputed
• accepted

Antonyms:

• challenged
• disputed

Meaning: Not controlled or restrained.

Part of speech: adjective

Example: Unchecked growth can lead to problems.

Category: Science › Biology

Synonyms:

• uncontrolled
• unrestrained

Antonyms:

• checked
• controlled

Meaning: Not regulated or restrained.

Part of speech: adjective

Example: The uncontrolled growth of weeds can harm the garden.

Category: Science › Biology

Synonyms:

• unchecked
• unregulated

Antonyms:

• controlled
• regulated

Meaning: Too many to be counted; infinite.

Part of speech: adjective

Example: There are uncountable stars in the sky.

Category: Science › Mathematics

Synonyms:

• innumerable
• countless

Antonyms:

• countable
• finite

Meaning: To reveal or expose something.

Part of speech: verb

Example: The investigation aimed to uncover the truth.

Category: Science › Research

Synonyms:

• reveal
• disclose

Antonyms:

• conceal
• hide

Meaning: Not covered or concealed.

Part of speech: adjective

Example: The uncovered area was exposed to the elements.

Category: Science

Synonyms:

• exposed
• revealed

Antonyms:

• covered
• concealed

Meaning: Not clearly defined or specified.

Part of speech: adjective

Example: The term was left undefined in the document.

Category: Science › Mathematics

Synonyms:

• ambiguous
• vague

Antonyms:

• defined
• clear

Meaning: Located or occurring beneath the sea.

Part of speech: adjective

Example: The undersea exploration revealed new marine species.

Category: Science › Marine Biology

Synonyms: submarine

Meaning: Not able to be discovered or identified.

Part of speech: adjective

Example: The virus was undetectable in the early stages.

Category: Science › Medicine

Synonyms:

• invisible
• hidden

Antonyms: detectable

Meaning: Not discovered or noticed.

Part of speech: adjective

Example: The error remained undetected for months.

Category: Science

Synonyms:

• unnoticed
• overlooked

Meaning: Not differentiated or distinct.

Part of speech: adjective

Example: The cells were undifferentiated and could develop into various types.

Category: Science › Biology

Synonyms:

• generic
• indistinct

Meaning: Not found or identified.

Part of speech: adjective

Example: There are many undiscovered species in the rainforest.

Category: Science

Synonyms:

• unfound
• hidden

Meaning: To discover something hidden or buried.

Part of speech: verb

Example: Archaeologists aim to unearth ancient artifacts.

Category: Science › Archaeology

Synonyms:

• discover
• reveal

Meaning: Not explained or clarified.

Part of speech: adjective

Example: There were many unexplained phenomena in the study.

Category: Science

Synonyms:

• unclear
• mysterious

Meaning: Not investigated or examined.

Part of speech: adjective

Example: The uncharted island remained unexplored.

Category: Science

Synonyms:

• untouched
• uninvestigated

Meaning: impossible to understand or measure.

Part of speech: adjective

Example: The depths of the ocean are unfathomable.

Category: Science › Oceanography

Synonyms:

• incomprehensible
• mysterious

Antonyms:

• comprehensible
• understandable

Meaning: Consisting of a single cell.

Part of speech: adjective

Example: Bacteria are unicellular organisms.

Category: Science › Biology

Synonyms: single-celled

Antonyms: multicellular

Meaning: Not able to be recognized or identified.

Part of speech: adjective

Example: The source of the noise was unidentifiable.

Category: Science

Synonyms: unknown

Antonyms: identifiable

Meaning: A substance that changes color to indicate pH levels.

Part of speech: noun

Example: The universal indicator is used in chemistry experiments.

Category: Science › Chemistry

Meaning: The time standard used worldwide, also known as Coordinated Universal Time (UTC).

Part of speech: noun

Example: Universal Time is used for international timekeeping.

Category: Science › Timekeeping

Synonyms: UTC

Meaning: All existing matter, space, and energy considered as a whole.

Part of speech: noun

Example: The universe is vast and full of mysteries.

Category: Science › Astronomy

Synonyms: cosmos

Meaning: not carrying a load or burden.

Part of speech: adjective

Example: The unladen ship sailed smoothly across the sea.

Category: Science

Synonyms:

• empty
• light

Antonyms:

• laden
• loaded

Meaning: Not demonstrated to be true or valid.

Part of speech: adjective

Example: The theory remains unproven.

Category: Science › Research

Synonyms:

• unverified
• untested

Antonyms:

• proven
• verified

Meaning: Not documented or officially noted.

Part of speech: adjective

Example: Many unrecorded species exist in the rainforest.

Category: Science › Biology

Synonyms:

• unnoted
• unregistered

Antonyms:

• recorded
• documented