to quack like a duck

Make mallard sounds

To quack like a duck is to make the harsh, flat sound characteristic of ducks—a nasal honking typically rendered as "quack quack." The phrase often appears in tests of obviousness: If it looks like a duck and quacks like a duck, it's probably a duck.

Someone who quacks like a duck is displaying unmistakable identifying characteristics.

authenticity

waddle

Swaying, clumsy gait

mallardCommon dabbling waterfowl
ducklingImmature waterfowl offspring
waterfowlSwimming birds collectively

pond · bill · webbed · feathers · paddle · drake · hen · flock · dabble · splash

imitation

mimic

One who copies others

parrotSpeech-mimicking tropical bird
echoReflected sound wave
copyIdentical reproduction made

ape · impersonate · mock · emulate · simulate · mirror · sound effect · replicate · imitate · rendition

quackery

charlatan

Faker claiming false expertise

fraudIntentional criminal trickery
fakeNot the real thing
phonyFraudulent person or thing

impostor · sham · snake oil · mountebank · pretender · huckster · con artist · scam · hoax · pseudoscience

Family

duck, quack, ducking, ducked, quacking, quacked, quacks, ducklike

Familiarity: Top 50,000
Profile: Known to kids · Used worldwide · Timeless · Concrete · Everyday, not technical · Rated G