Jerky describes movement that comes in sudden uneven bursts instead of flowing. A lift that starts with a lurch, a learner driver's first ten metres, an old film where everyone walks too fast and stops too hard.
It is the adjective built from jerk: a jerky camera, a jerky handshake, jerky breathing after someone has been crying. The adverb is jerkily and the noun is jerkiness. Jerky is also a food, and there it is a completely separate word — strips of beef salted and dried until they are dark and chewy, sold in bags at petrol stations. Nothing about that meat is jerky in the movement sense. In American English there is a third use: a jerky remark is one made by someone behaving like a jerk.
1adjectivejerkyMoving in sudden uneven starts rather than smoothly.
“The old projector gave the horses a jerky, hurried walk.”
synonyms: jolting, uneven
2nounstripsStrips of meat salted and dried until they are dark and chewy.
“He lived on coffee and beef jerky for the whole drive.”
3adjectiverudeRude and inconsiderate, like a jerk. Informal, American English.
“That was a jerky thing to say to her in front of everyone.”
The chewy meat kind of jerky has nothing to do with jerking. It was borrowed from Spanish charqui, and Spanish had it from Quechua charki, a language of the Andes. The word travelled with the food, out of the mountains and into English by way of Spain.
Middle English
yerk — sudden motion
English
jerk
English, today
jerky
From jerk + -y. jerk Probably from Middle English yerk (“sudden motion”) and Middle English yerkid (“tightly pulled”), from Old English ġearc (“ready, active, quick”) and Old English ġearcian (“to prepare, make ready, procure, furnish, supply”). Cognate with Scots yerk (“to jerk”). Related also to yare (“ready”).
Etymology from Wiktionary, CC BY-SA