From Old Norse 'þéttr' (watertight, dense), from Proto-Germanic *þinhtaz — originally about density and impermeability.
Fixed, fastened, or closed firmly; fitting closely.
From Middle English 'thight' (dense, solid), from Old Norse 'þéttr' meaning 'watertight, close, solid,' from Proto-Germanic *þinhtaz (thick, dense). Originally meant 'dense' or 'watertight.' Key roots: *þinhtaz (Proto-Germanic: "dense, thick").