extro-

word-forming element meaning "outside; beyond the scope of; in addition to what is usual or expected," in classical Latin recorded only in extraordinarius, but more used in Medieval Latin and modern formations; it represents Latin extra (adv.) "on the outside, without, except," the old fem. ablative singular of exterus "outward, outside," comparative of ex "out of" (see ex-).

word-forming element, from Latin intro (adv.) "in, on the inside, within, to the inside," from PIE *en-t(e)ro-, suffixed form of root *en "in."

mid-17c., "condition of being turned inside out," noun of action from obsolete verb extrovert (v.) "to turn inside out," from extro- + Latin vertere "to turn" (from PIE root *wer- (2) "to turn, bend"). Earliest as a word in mysticism; modern use in psychology attested by 1920.