Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
supplementary, complementary (adjs.)
Something supplementary is something additional: I was well fed, but I still watched for Mother’s supplementary food packages. Something complementary is something that makes up for what is missing, especially something lacking in one of a pair: The partners’ personalities were complementary; one was talkative, the other taciturn. See also COMPLEMENTARY.
