Etymology: Adopted in end of 17th cent. from French compliment, 16th cent. < Italian complimento , ‘expression of respect and civility to another by words or by acts’. The Latin complēmentum , Romanic complimento , became in Old French complement (compliement ), in Italian compimento , with the original sense of ‘filling up, fulfilment, accomplishment’; in Old Catalan complimento , Spanish cumplimiento , there was a special development of use, as in the verb (see comply v.¹), giving the sense ‘observance or fulfilment of the requirements and forms of courtesy’, which was adopted in Italian in the form complimento , and thence passed into French and English. Compliment is thus a doublet of complement n. (the form directly < Latin). The latter was in use in this sense about a century before the introduction of the French word, which slowly took its place between 1655 and 1715: see complement n. 9, where the earlier history of this sense may be seen; compare also comply v.¹H. L'Estrange's comply-ment , compli-ment (in sense 1a, 1b), appear to have been formed for the nonce on comply v.¹, before compliment was in English use. Compare Skinner, 1668–71 ‘complement < French compliment, Italian complimento, hæc a verbo to Comply, q.d. Comply-ments’. (From c1700–17 to the present day nearly all editions of 16th cent. works, whether re-issues of printed books or original editions from manuscript (e.g. Clarendon's History, Pepys' Diary, Letters of Dorothy Osborne, etc.), systematically alter the original spelling complement into compliment, as do also modern dictionaries in their alleged quotations; only contemporary documents supply evidence as to the introduction of the French form.)

Etymology: < French complimente-r, < compliment : see compliment n. Pronounced by some with stress on first syllable; but the final syllable is always clear.