n. A five-membered heterocycle having one carbon atom, four nitrogen atoms and two double bonds
the GNU version of the Collaborative International Dictionary of English
n. A crystalline acid substance, CH2N4, which may be regarded as pyrrol in which nitrogen atoms replace three CH groups; also, any of various derivatives of the same.
The Century Dictionary and Cyclopedia
n. A colorless compound, prepared from aminophenyltetrazole-carboxylic acid. It has acidic properties, crystallizes in lustrous prisms or plates, melts at 155° C., and may be sublimed.