1570s, "transposition of letters in a word;" c.1600, "rhetorical transposition of words," from Late Latin metathesis, from Greek metathesis "change of position, transposition, change of opinion," from stem of metatithenai "to transpose," from meta- "to change" (see meta-) + tithenai "to place, set" (see theme). Plural is metatheses. Related: Metathetic.