'applaud' originates from Latin, specifically the word 'applaudere', where 'ad-' meant 'to, toward' and 'plaudere' meant 'to strike (the hands)'.

'applaud' entered English via Middle French/Latin influence (e.g. French aplaudir) and through Early Modern English the verb became 'applaud'; the adverb 'applaudingly' is formed by adding the suffixes -ing and -ly to the verb.

Initially, it meant 'to strike the hands together' (i.e. clap); over time it broadened to mean 'to express approval or praise', and 'applaudingly' now conveys doing so (often by clapping) or expressing approval.