Other forms: cracks, cracked, cracking
To crack is to break something with a sharp knock — crack an egg, crack a nut — or for something to develop a line without falling apart: the glass cracked.
The noun covers the line, the sound and the gap: a crack in the wall, the crack of a whip, the door was open a crack. From those come a busy set of uses. Crack a joke, crack a code, crack under pressure, have a crack at something. And crack of dawn means very early. Note that crack is also a drug, which is why the word occasionally needs care in context.
1verbcrackTo break something open with a sharp knock.
“Crack two eggs into the bowl.”
Patterncrack + noun (an egg, a nut, a code) · crack sth open · crack the whip · a cracked cup
2nounthinA thin line where something has broken but not come apart.
“There is a crack running right across the ceiling.”
3nounsuddenA sudden sharp sound.
“There was a crack and then a long silence.”
4verbsolveTo solve something difficult.
“Nobody cracked the code for eleven years.”
5verbsplitTo break so that thin lines appear in the surface, without falling apart.
“The windscreen cracked when a stone flew up from the lorry in front.”
Too few real examples of this word to estimate which sense is commonest.
CRACK → the sound of an egg on the bowl
Knock the egg on the edge of the bowl: crack, and the shell opens.
Old English cracian meant to resound or make a sharp noise. The word is imitative and the breaking sense came from the sound, not the other way round — which is why the crack of a whip, where nothing breaks, is closer to the original.
Old English
cracian
Middle English
crakken
English, today
crack
From Middle English crakken, from Old English cracian. From Middle English crakken, craken, from Old English cracian (“to resound, crack”), from Proto-West Germanic krakōn (“to crack, crackle, shriek”), ultimately from Proto-Indo-European gerh₂- (“to resound, cry hoarsely”). Cognate with Scots crak (“to crack”), West Frisian kreakje (“to crack”), Dutch kraken (“to crunch, creak, squeak”), Low German kraken (“to crack”), German krachen (“to crash, crack, creak”), Lithuanian gìrgžděti (“to creak, squeak”), xcl կարկաչ, Sanskrit गर्जति (“to roar, hum”).
Etymology from Wiktionary, CC BY-SA