Multiple origins merged: 'pointed end' from Old Norse 'typpi,' 'gratuity' from slang, 'advice' from 'tip off.'
The pointed end of something; a small sum of money given for service; a useful piece of advice.
The 'pointed end' sense possibly from Old Norse 'typpi' (tip, top). The 'gratuity' sense (1610s) may be from thieves' slang 'tip' (to give, hand over). The 'advice' sense (1880s) may be from 'tip off' (to warn). Key roots: typpi (Old Norse