Sudden, sharp, or abrupt movements, or plural of jerk, a rude or obnoxious person.
Possibly from Dutch 'jurken' or German 'zucken' meaning to tug or pull. The word evolved from describing a physical pulling motion to describing a person who 'jerks' emotionally or socially.
In weightlifting, a 'jerk' is an actual technical lift move, but in slang a 'jerk' is a person who behaves unexpectedly mean—both meanings come from the same root of sudden movement, showing how a physical action word became a character insult.
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