1530s, "to express agreement with," from L. applaudere
"to clap the hands in approbation, to approve by clapping hands," from ad
"to" + plaudere
"to clap" (see plaudit
). Sense of "express approval of" is from 1590s; that of "to clap the hands" is from 1590s. Figurative sense arrived in English before literal.