Origin and history of transmutable

late 14c., transmuten, "transform the appearance of," from Latin transmutare "change from one condition to another," from trans "across, beyond; thoroughly" (see trans-) + mutare "to change" (from PIE root *mei- (1) "to change, go, move").

As "change from one nature, form, or substance to another," by late 15c., specifically in alchemy, "change baser metals to ones of more value." Related: Transmuted; transmuting. Also transmutative, transmutatory (1610s)., The verb's longer and less common form transmutate (1630s) is from the Latin past-participle stem.