Is 'micra' commonly used today?

No, it is considered archaic or highly specialised. 'Micrometres' or the singular 'micron' are the standard terms.

Can I use 'micra' in my academic essay?

It is not recommended unless you are directly quoting an older source or writing within a very specific field that still uses this terminology.

Why does this plural form exist?

It comes from the Greek/Latin origin of the word 'micron'. Similar to 'phenomenon/phenomena' or 'criterion/criteria'.

Is “micra” formal?

Micra is usually highly technical/scientific; formal written. in register.

How do you pronounce “micra”?

Micra: in British English it is pronounced /ˈmʌɪkrə/, and in American English it is pronounced /ˈmaɪkrə/. Tap the audio buttons above to hear it.

micra: meaning, definition, pronunciation and examples

Rare

UK/ˈmʌɪkrə/US/ˈmaɪkrə/

Highly technical/scientific; formal written.

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Quick answer

What does “micra” mean?

plural of micron (one millionth of a metre).

Audio

Pronunciation

Definition

Meaning and Definition

plural of micron (one millionth of a metre).

Used primarily in scientific/technical contexts to denote extremely small units of measurement; sometimes used figuratively for minute details or particles.

Dialectal Variation

British vs American Usage

Differences

No significant difference in usage, as the term is confined to highly technical fields. Both regions now prefer 'micrometres' or 'microns'.

Connotations

Pedantic or archaic if used outside of very specific historical or specialised technical texts.

Frequency

Extremely low in both varieties. More likely found in older British engineering or physics texts than contemporary American ones.

Grammar

How to Use “micra” in a Sentence

[Number] + micra + in + [dimension (diameter, thickness)][Verb +] + under + [number] + micra

Vocabulary

Collocations

strong

measured in micraa few micraparticles of a few micra

medium

diameter of X micraless than 10 micra

weak

precise to the micramicra thick

Usage

Meaning in Context

Business

Virtually never used.

Academic

Only in historical or very specific technical papers (e.g., materials science, physics).

Everyday

Never used.

Technical

The primary domain, but even here 'micrometres' or 'microns' is standard.

Vocabulary

Synonyms of “micra”

Strong

microns

Neutral

micrometresμm

Weak

millionths of a metre

Vocabulary

Antonyms of “micra”

kilometresmileslarge units

Watch out

Common Mistakes When Using “micra”

Using 'micra' as a singular noun.
Pronouncing it /mɪˈkrɑː/.
Using it in non-technical writing.
Confusing it with 'micro' as a prefix.

FAQ

Frequently Asked Questions

: No, it is considered archaic or highly specialised. 'Micrometres' or the singular 'micron' are the standard terms.
: The singular is 'micron'.
: It is not recommended unless you are directly quoting an older source or writing within a very specific field that still uses this terminology.
: It comes from the Greek/Latin origin of the word 'micron'. Similar to 'phenomenon/phenomena' or 'criterion/criteria'.
: plural of micron (one millionth of a metre).
: Micra is usually highly technical/scientific; formal written. in register.
: Micra: in British English it is pronounced /ˈmʌɪkrə/, and in American English it is pronounced /ˈmaɪkrə/. Tap the audio buttons above to hear it.

Phrases

Idioms & Phrases

“Not to the nearest micra (not hyper-precise)”
“Arguing over micra (disputing trivial details)”

Learning

Memory Aids

Mnemonic

Think: 'Micro' means small; 'Micra' are small 'A'-lots of them (the plural).

Conceptual Metaphor

PRECISION IS SMALLNESS; TRIVIALITY IS MINUTE SIZE.

Practice

Quiz

Fill in the gap

In the old textbook, the pollen grains were described as being 15 to 20 in diameter.

Multiple Choice

Which of the following is the MOST appropriate context for the word 'micra'?