The word 'though' originates from the Old English word 'þēah', which meant 'though, although, however'. This Old English term is cognate with Old Saxon 'thōh' and Old High German 'doh', all sharing a similar meaning. It is ultimately traced back to the Proto-Germanic 'þauh', a conjunction with a concessive sense. The modern spelling and pronunciation evolved through Middle English forms like 'thah', 'thogh', and 'thouh', gradually solidifying into the current form 'though', while retaining its core function of introducing a contrasting or qualifying clause.

The word 'though' is a simplex word derived from a single Old English root. It does not contain separable morphemes in its modern English spelling.