Other forms: creaking, creaks, creaked
To creak is to make that long, complaining squeak old wood makes when it takes weight. The third stair when you come in late, a garden gate, a rocking chair, the door in every ghost story ever filmed.
Creak is a noun as well — a creak on the landing — and the adjective is creaky: a creaky floorboard, a creaky old bed. It stretches to anything under strain and close to giving way: a booking system creaking under demand, an old bridge creaking in the wind. Do not mix it up with creek, a small stream, which sounds much the same, and do not mix it up with squeak, which is shorter and higher, the noise of a mouse or a wet shoe. Things creak and people rarely do — a knee can creak, but a person groans. The sound is slow: a hinge creaks open across a whole second, and that slowness is the whole picture.
1verbcreakTo make a long, high, complaining sound, the way old wood does under weight.
“The stairs creak whichever side you tread on.”
2nounlongThat long, complaining sound.
“There was a creak on the landing, then nothing at all.”
3verbshowTo show strain and be close to failing.
“The whole booking system creaks every time tickets go on sale.”
Too few real examples of this word to estimate which sense is commonest.
Creak is a copy of a noise. Old English cearcian meant to chatter, creak, crash, gnash, and Middle English shuffled its letters into creken. Behind that stand Proto-West Germanic *krakōn, to crash, crack, creak, and a Proto-Indo-European root *gerh₂-, to make a sound, to cry hoarsely. Crack is a cousin, which is why the two words feel like the same family of noise.
Proto-Indo-European
*gerh₂- — to make a sound, cry hoarsely
Proto-West Germanic
*krakōn — to crash, crack, creak
Old English
cearcian — to chatter, creak, crash, gnash
Middle English
creken
English, today
creak
From Middle English creken, criken, metathesis of Old English cearcian (“to chatter, creak, crash, gnash”), from Proto-West Germanic krakōn (“to crash, crack, creak”), from Proto-Indo-European gerh₂- (“to make a sound, cry hoarsely”), ultimately of imitative of the sound origin. Compare also Old English crǣccettan, crācettan (“to croak”), Albanian grykë (“throat”). More at crack.
Etymology from Wiktionary, CC BY-SA