1590s, "thin, unsubstantial," irregularly formed from Latin tenuis "thin, drawn out, meager, slim, slender," figuratively "trifling, insignificant, poor, low in rank," from PIE root *ten- "to stretch," + -ous. The correct form with respect to the Latin is tenuious. The figurative sense of "having slight importance, not substantial" is found from 1817 in English. Related: Tenuously; tenuousness.
updated on April 17, 2017