# MOL

/ˈmɔɫ/ (US) · CEFR C1 · Noun

Source: https://englishreference.com/word/mol
Updated: 2026-05-08

## Definition

a standard unit in science used to measure the amount of a substance. It helps scientists count very tiny things like atoms or molecules by grouping them into a specific, large number.

For teachers: the SI base unit for the amount of a substance, defined as exactly 6.02214076 × 10²³ elementary entities. Used to express the magnitude of chemical reactions and the proportions of elements in a compound.

## Pitfalls

- Not "three mol of water" but "three moles of water" — While 'mol' is the official scientific symbol, the full word 'moles' should be used in standard English sentences.

## Usage notes

- Often followed by 'of' and the name of a specific element or molecule.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.