extenuate

From Middle English extenuat (“(medicine) made thin, emaciated”), from Latin extenuātus (“diminished, reduced, thinned”), perfect passive participle of extenuō (“to diminish, reduce, thin”) (see -ate (verb-forming suffix)), from ex- (“out-, thoroughly”) + tenuō (“to enfeeble, weaken, wear down; to lessen, reduce; to make thin”) from tenuō, itself from tenuis (“fine, slender, thin; feeble, weak”) + -ō (first conjugation-verb forming suffix) (ultimately from Proto-Indo-European *tenh₂- (“to extend, stretch; thin”)). Compare attenuate.

From Latin extenuātus (“diminished, reduced, thinned”) (more at etymology 1), see -ate (adjective-forming suffix).