'structural isomer' definitions:

Definition of 'structural isomer'

From: GCIDE

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]