late 14c., "philosopher of the school founded by Zeno," from Latin stoicus, from Greek stoikos "pertaining to a member of or the teachings of the school founded by Zeno (c. 334-c. 262 B.C.E.), 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). Meaning "person who represses feelings or endures patiently" first recorded 1570s. The adjective is recorded from 1590s in the "repressing feelings" sense, c. 1600 in the philosophical sense. Compare stoical.
suffix forming nouns of action from verbs, mostly from Latin and French, meaning "act of ______ing" (such as survival, referral), Middle English -aille, from French feminine singular -aille, from Latin -alia, neuter plural of adjective suffix -alis, also used in English as a noun suffix. Nativized in English and used with Germanic verbs (as in bestowal, betrothal).
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Harper, D. (n.d.). Etymology of stoical. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/stoical