Word
quantum
Phoneticsquan·tum, stress on the first syllable
US/ˈkwɑntəm/
UK/kwˈɒntəm/
Definitions
01physics unit
C1 · Advanced Countable noun Science Technical
n. the smallest possible unit of energy, such as light.
n. the smallest discrete unit of a physical quantity, such as energy or momentum.
“In physics, a photon is a single quantum of light.”
“The theory proposes that energy is not continuous but is instead emitted in discrete packets known as quanta.”
Usage
The plural form is 'quanta'.
02total amount
C1 · Advanced Countable noun Formal
n. a specific amount or the total quantity of something.
n. a required or allowed amount; the total sum or quantity of something.
“The court had to decide the quantum of damages the company should pay.”
“The judge spent several hours determining the appropriate quantum of compensation for the claimant's loss of earnings.”
Usage
Commonly used in legal contexts regarding money or damages.
03a big change
B2 · Upper Intermediate
adj. used to describe a change that is very sudden, big, or important.
adj. relating to a sudden, significant, or discrete change that moves something to a higher level.
“The new invention was a quantum leap in mobile phone technology.”
“The transition from steam power to electricity represented a quantum shift in industrial productivity.”
Teaching tip
Often used in the fixed phrase 'quantum leap' or 'quantum shift' to mean a huge improvement.
Synonyms
04quantum physics
C1 · Advanced Science Technical
adj. relating to the branch of physics that studies very small particles.
adj. pertaining to quantum mechanics or the subatomic properties of matter and energy.
“Scientists are working hard to build the first reliable quantum computer.”
“Quantum entanglement remains one of the most counterintuitive phenomena in modern theoretical physics.”
Real-World Examples
“His research is the bluest of blue-sky: he uses quantum computers to predict how sub-atomic particles behave.” “Physicists have found a new way to peer inside one of matter’s most elusive quantum states: the Wigner crystal, where electrons stop behaving like independent particles and organize into a crystal-like pattern.” “Scientists have created the first quantum material that can sort and transport different quantum states of light at room temperature, potentially removing the need for bulky, ultra-cold refrigeration systems.” “Scientists have generated quantum entanglement directly from sunlight, potentially offering a lower-energy alternative to the lasers normally used in quantum technology.” Etymology
From Late Latin quantum, noun use of neuter form of Latin quantus (“how much”).
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.
Idioms
01. quantum tunnel
Domains
- Exam level
- CambridgeCambridgeCambridge English QualificationsThe exam suite from Cambridge University Press & Assessment, from A1 Movers up to C2 Proficiency. The benchmark names double as CEFR labels.C2 ProficiencyIELTSIELTSInternational English Language Testing SystemThe 0–9 band test co-owned by the British Council, IDP, and Cambridge. Used for university entry, work, and migration.8.5–9.0TOEFL iBTTOEFL iBTTest of English as a Foreign Language, Internet-Based TestETS's academic English test, the standard route for US university admissions. Scored 0–120, with a 1–6 scale since 2026.1–6 scale: 6.0114–120
- Frequency
- Common
- Level
- C2 · Proficiency
- Updated
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