canary in the coal mine

Register · Neutral Neutral — appropriate in most situations, both spoken and written, without sounding too casual or too stiff. CEFR C1

Post

Figurative meaning

an early warning sign, or a small test group, that reveals a danger or failure before it affects everyone

Why this phrase?

Miners carried canaries: the birds died from gas leaks before the men did. In software, a canary deployment tests a release on a small slice of traffic.

Example

“Roll the feature out to 5% of users first — that's our canary in the coal mine.”

Dictionary details

Alternate forms

Component words

canary coal mine

Tags

Expressions connected by reviewed component words or topic tags.

band-aid fix Informal · CEFR B2

a hasty, temporary solution that patches a symptom without addressing the root cause

feature creep Neutral · CEFR B2

the uncontrolled growth of new features until a product becomes bloated and hard to use

keep tabs on Informal · CEFR B2

to monitor someone or something carefully over time

nip it in the bud Neutral · CEFR B2

to stop a problem at an early stage

quick and dirty Informal · CEFR B2

done rapidly and roughly, with little care for quality or polish

smoke test Neutral · CEFR B2

a quick, shallow test that checks whether a system's most basic functions work at all

Source methodology

Meanings, register, CEFR, and examples come from the reviewed dictionary record. Expression notes may describe a reviewed present-day word picture or a background note; they are not presented as verified etymology.

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