Source : Webster's Revised Unabridged Dictionary (1913)

Tho \Tho\, adv. [AS. [thorn][=a].]
   Then. [Obs.] --Spenser.

         To do obsequies as was tho the guise.    --Chaucer.

Tho \Tho\, conj.
   Though. [Reformed spelling.]

Tho \Tho\, pron. pl.
   Those. [Obs.]

         This knowen tho that be to wives bound.  --Chaucer.

Tho \Tho\ ([th][=o]), def. art.
   The. [Obs.] --Spenser.

Source : WordNet®

Tho
     n : a branch of the Tai languages