Entry 1 sense Webster, 1913 Placid /plăs'-əd/ · Plac·id · IPA /ˈplæs.ɪd/ 01 a. Pleased; contented; unruffied; undisturbed; serene; peaceful; tranquil; quiet; gentle. 1. Pleased; contented; unruffied; undisturbed; serene; peaceful; tranquil; quiet; gentle.