if it looks like a duck, swims like a duck, and quacks like a duck, then it probably is a duck
Proposed by a contributor, not yet supported by evidence.
Meaning · English
English proverb; full definition pending editorial review.
Sources & notes
Listed on English Wikiquote “English proverbs” (CC BY-SA 4.0, retrieved 2026-07-31).
Common questions
What does “if it looks like a duck, swims like a duck, and quacks like a duck, then it probably is a duck” mean?
English proverb; full definition pending editorial review.
Is “if it looks like a duck, swims like a duck, and quacks like a duck, then it probably is a duck” formal or informal?
No register label has been reviewed yet — treat it as neutral and check the usage notes above.