As an adjective isomeric
is (chemistry|physics) being an isomer.
As a noun butenyl is
(organic chemistry) any of several isomeric univalent radicals derived from butene; but especially crotyl.
isomeric
English
Adjective
(-)
(chemistry, physics) Being an isomer.
(chemistry) Exhibiting isomerism.
butenyl
English
Noun
(
en noun)
(organic chemistry) Any of several isomeric univalent radicals derived from butene; but especially crotyl