'applaud' originates from Latin, specifically the word 'applaudere', where 'ad-' meant 'to/toward' and 'plaudere' meant 'to clap or strike.'

'applaud' passed into English via Old French 'applaudir' and Middle English forms (e.g. 'applauden'), eventually becoming the modern English 'applaud' and the agent noun 'applauder'.

Initially it meant 'to clap (one's hands)', and over time it came to mean specifically 'to clap to show approval or praise,' a meaning that has largely remained.