(1):

(v. i.) To use the words thou and thee in discourse after the manner of the Friends.

(2):

(v. t.) To address as thou, esp. to do so in order to treat with insolent familiarity or contempt.

(3):

(obj.) The second personal pronoun, in the singular number, denoting the person addressed; thyself; the pronoun which is used in addressing persons in the solemn or poetical style.