1625-35; < Medieval Latindēcanthāre, equivalent to Latindē-de- + Medieval Latincanth(us) spout, rim of a vessel (Latin: iron band round a wheel < Greekkánthos corner of the eye, tire) + -āre infinitive suffix
1630s, "pour off the clear liquid from a solution by gently tipping the vessel," originally an alchemical term, from Fr. decanter, from M.L. decanthare, from canthus "corner, lip of a jug," from Gk. kanthos "corner of the eye," on a perceived resemblance between the beaked lip of a jug and the corner of the eye.