n. [ Pref. tri- + sulphonal; -- so called because it contains three ethyls. ] (Chem.) A compound similar to sulphonal, used as a hypnotic in medicine. [ Webster 1913 Suppl. ]
a. Having three angles, or corners; triangular; as, a trigonal stem, one having tree prominent longitudinal angles. [ 1913 Webster ]
[ 1913 Webster ]