Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
tho, tho’ (adv., conj.)
Tho is a variant spelling of though; it has been in use for centuries, and it is frequently used in poetry and in Informal correspondence to suggest the informality of Conversational language. It occasionally still has an apostrophe to indicate the omitted letters. See SPELLING (2).
