megajoule: meaning, definition, pronunciation and examples
C2Technical, Scientific, Academic
Quick answer
What does “megajoule” mean?
A unit of energy in the International System of Units (SI), equal to one million joules.
Audio
Pronunciation
Definition
Meaning and Definition
A unit of energy in the International System of Units (SI), equal to one million joules.
A metric measurement used primarily in scientific, engineering, and dietary contexts to quantify large amounts of energy, work, or heat.
Dialectal Variation
British vs American Usage
Differences
No significant linguistic differences. Both dialects use the SI unit identically. Potential minor spelling preference for '-ise' vs. '-ize' in related words (e.g., 'energise' vs. 'energize') but not in the unit itself.
Connotations
Neutral technical term in both.
Frequency
Equally low frequency in general discourse but equally standard in technical contexts in both the UK and US.
Grammar
How to Use “megajoule” in a Sentence
[Number] megajoule(s) of [energy type]A [source] has an energy content of [Number] MJ.The [process] requires [Number] megajoules.Vocabulary
Collocations
Examples
Examples of “megajoule” in a Sentence
verb
British English
- Not applicable as a verb.
American English
- Not applicable as a verb.
adverb
British English
- Not applicable as an adverb.
American English
- Not applicable as an adverb.
adjective
British English
- The megajoule rating of the battery is impressive.
- We need a megajoule-class capacitor for this experiment.
American English
- They specified a megajoule output for the laser system.
- The device has a megajoule capacity.
Usage
Meaning in Context
Business
Used in energy sector reports, e.g., 'The new turbine has an output of 50 megajoules per second.'
Academic
Common in physics, engineering, and nutritional science papers, e.g., 'The reaction was measured to release 2.3 megajoules.'
Everyday
Rare. Might appear on nutritional labels in some countries (e.g., Australia) or in discussions about home energy bills.
Technical
The primary register. Used to specify quantities of energy in research, specifications, and industrial calculations.
Vocabulary
Synonyms of “megajoule”
Strong
Neutral
Weak
Vocabulary
Antonyms of “megajoule”
Watch out
Common Mistakes When Using “megajoule”
- Mispronouncing 'joule' to rhyme with 'foul' (correct: /dʒuːl/).
- Incorrect pluralisation ('megajoule' vs. 'megajoules').
- Confusing 'megajoule' with 'megawatt' (power vs. energy).
FAQ
Frequently Asked Questions
No. A megajoule (MJ) is a unit of energy. A megawatt (MW) is a unit of power (energy per second). 1 MW for 1 second delivers 1 MJ of energy.
Most commonly on food packaging in countries like Australia and New Zealand, where food energy is labelled in kilojoules and megajoules (1 MJ = 1000 kJ), instead of Calories.
It is pronounced /ˈmɛɡədʒuːl/. Stress on the first syllable 'MEG-a', and 'joule' sounds like 'jewel'.
No, it is exclusively a noun. You cannot 'megajoule' something.
A unit of energy in the International System of Units (SI), equal to one million joules.
Megajoule is usually technical, scientific, academic in register.
Phrases
Idioms & Phrases
- “Not applicable for this technical term.”
Learning
Memory Aids
Mnemonic
Think of a MEGA-sized jewel (sounds like 'joule') that stores a huge amount of energy. 'Mega-' means million, so it's a million jewels/joules of energy.
Conceptual Metaphor
ENERGY IS A MEASURABLE SUBSTANCE (we quantify it in containers/units like megajoules).
Practice
Quiz
Which of the following best describes a megajoule?