Compounds bearing the group N3, viz. –N=N+=N−; usually attached to carbon, e.g. PhN3 phenyl azide or azidobenzene.
Salts of hydrazoic acid, HN3, e.g. NaN3 sodium azide.
Source: PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1320 (https://doi.org/10.1351/pac199567081307)