[thou] pron [ME, fr. OE thu; akin to OHG du thou, L tu, Gk sy] (bef. 12c) archaic: the one addressed "~ shalt have no other gods before me --Exod 20:3 (AV)"--used esp. in ecclesiastical or literary language and by Friends as the universal form of address to one person--compare thee, thine, thy, ye, you
[2]thou vt (15c): to address as thou [3]thou n, pl thou [short for thousand] (1867): a thousand of something (as dollars)