(1):
A hypothetical compound, C2H2N4 which may be regarded as benzene with four CH groups replaced by nitrogen atoms; also, any of various derivatives of the same. There are three isomeric varieties.
(2):
A sirupy, nontoxic ptomaine, C5H14N2 (chemically pentamethylene diamine), formed in putrefaction of flesh, etc.
(3):
A suffix. See the Note under -ine.