1847, back-formation from allotropy "variation of physical properties without change of substance," from Greek allotropos "in another manner;" see allo- "different" + -trope "way, manner." Diamond is an allotrope of carbon. Related: Allotropic.
graphite and diamond are allotropes of carbon
allopathic
allopathy
allot
allotheism
allotment
allotrope
allotropy
all-over
allow
allowable
allowance