bromide (n.)

nonmetallic element, 1827, from French brome, from Greek bromos "stench," a word of unknown etymology. With chemical suffix -ine (2). The evil-smelling dark red liquid was discovered by French chemist Antoine Jérôme Balard (1802-1876), who initially called it muride.

word-forming element used in chemistry to coin names for simple compounds of one element with another element or radical; originally abstracted from oxide, which was the first so classified, in which the -ide is from acide "acid."

The suffix is really -dus (-do-), the -i- repr. the orig. or supplied stem-vowel ; it occurs without the vowel in absurdus, absurd, blandus, bland, crudus, raw (crude), etc. [Century Dictionary]