Meaning

verb move up and down repeatedly

noun a former monetary unit in Great Britain

noun a hair style for women and children; a short haircut all around

originFrom Middle English bobben (“to strike, beat, shake, jog”), of uncertain origin. Compare Scots bob (“to mark, dance with a bobbing motion”), Icelandic boppa (“to wave up and down”), Swedish bobba (“to bob”), Dutch dobberen ("bobbing").

Etymology from Wiktionary, CC BY-SA 3.0