The Collaborative International Dictionary of English v.0.48:

Bromine \Bro"mine\, n. [Gr. ? bad smell, stink. Cf. Brome.]
   (Chem.)
   One of the halogen elements, related in its chemical
   qualities to chlorine and iodine. Atomic weight 79.8. Symbol
   Br. It is a deep reddish brown liquid of a very disagreeable
   odor, emitting a brownish vapor at the ordinary temperature.
   In combination it is found in minute quantities in sea water,
   and in many saline springs. It occurs also in the mineral
   bromyrite.
   [1913 Webster]

WordNet (r) 3.0 (2006):

bromine
    n 1: a nonmetallic heavy volatile corrosive dark brown liquid
         element belonging to the halogens; found in sea water [syn:
         bromine, Br, atomic number 35]

The Elements (07Nov00):

bromine
Symbol: Br
Atomic number: 35
Atomic weight: 79.909
Halogen element. Red volatile liquid at room temperature. Its reactivity
is somewhere between chlorine and iodine. Harmful to human tissue in a
liquid state, the vapour irritates eyes and throat. Discovered in 1826
by
Antoine Balard.