-idine

Also ‑etidine, ‑iridine, and ‑olidine.

Organic ring compounds containing nitrogen.

From ‑ide plus ‑ine³.

Such names often imply a compound derived from another; for example toluidine is toluene plus a nitrogen-containing amino group; xylidine, a dye intermediate, is similarly xylene with an amino group added.

These examples are derivatives of monocyclic hydrocarbons; the ending also appears in names for compounds with two rings, such as benzidine, another dyestuff intermediate, formed from biphenyl. It also occurs in some names of alkaloids (quinidine, an isomer of quinine), certain nucleosides (cytidine, a nucleoside obtained from RNA by hydrolysis), and some heterocyclic compounds (piperidine, a peppery-smelling liquid used as a solvent).

In systematic chemical naming, the derived forms ‑iridine, ‑etidine, and ‑olidine refer to saturated heterocyclic rings containing nitrogen with respectively three, four, and five atoms in the ring (examples are aziridine, phenetidine, and pyrrolidine).