CH3CH2NH2

Isomer I"so*mer ([imac]"s[-o]*m[~e]r), n. [See {Isomeric}.] (Chem.) A compound which is isomeric with another body or compound; a compound having the same chemical composition as another compound; a member of an isomeric series. [1913 Webster +PJC]

Note: An isomer may be a {structural isomer}, in which some of the atoms are bonded to different atoms (as in {CH3.CH2.NH2} and {CH3.NH.CH3}), or an {optical isomer}, in which the number and types of chemical bonds are identical, but the arrangement of the atoms in three-dimensional space is different; the latter are also called {stereoisomers}. [PJC]