Verb for Thou' is a phrase used to describe the second-person singular conjugation of verbs in the English language. The three crossword solutions, DOST, DOEST, and SAYST, are all examples of this conjugation. DOST is the present tense form of the verb 'DO, ' DOEST is the past tense form of the verb 'DO, ' and SAYST is the present tense form of the verb 'SAY.' All three words are used to refer to a single person, usually the person being addressed.