D defs.my
Entry 3 senses Webster, 1913

Bromide

/brō'mīd/ · Bro·mide · IPA /ˈbɹoʊ.maɪd/
01 n. A compound of bromine with a positive radical.
  1. 1.
    A compound of bromine with a positive radical.(Chem.)
  2. 2.
    A person who is conventional and commonplace in his habits of thought and conversation.[Slang]
    “The bromide conforms to everything sanctioned by the majority, and may be depended upon to be trite, banal, and arbitrary.” — Gelett Burgess.
  3. 3.
    a conventional or trite saying; -- often used in the phrase “old bromide”.