lang syne I. \(ˈ)laŋˈzīn, (ˈ)laiŋ-, -ˈsīn\adverb (or adjective) Etymology: Middle English (Scots) lang sine, from lang long + sine, syne since — more at long, syne chiefly Scotland: at a distant time in the past II. noun chiefly Scotland: times past : old times < old men sat … and talked politics, racing, or lang syne — Ruth Park >