stoic (n.)

late 14c., "philosopher of the school founded by Zeno" (c. 334-c. 262 B.C.E.), from Latin stoicus, from Greek stoikos "pertaining to a member of or the teachings of the school founded by Zeno, characterized by austere ethical doctrines," literally "pertaining to a portico," from stoa "porch," specifically Stoa Poikile "the Painted Porch," the great hall in Athens (decorated with frescoes depicting the Battle of Marathon) where Zeno taught (see Stoa).

Old English had Stoices (plural); Middle English had Stoiciens. The general meaning "person not easily excited, person who represses feelings or endures patiently" is recorded by 1570s. The adjective is recorded from 1590s in the "repressing feelings" sense, c. 1600 in the philosophical sense. Compare stoical.