- the second person singular subject pronoun, equivalent to modern you (used to denote the person or thing addressed): Thou shalt not kill.
- (used by Quakers) a familiar form of address of the second person singular: Thou needn’t apologize.
- to address as “thou,” especially during an era of historical English when “thou” was distinguished as an informal form of you: It would have been scandalous for household staff to thou the lord of the manor.
- to use “thou” in discourse: There are still Quakers who thou as a matter of custom.
- one thousand dollars, pounds, etc.
- refers to the person addressed: used mainly in familiar address or to a younger person or inferior
- refers to God when addressed in prayer, etc
- one thousandth of an inch. 1 thou is equal to 0.0254 millimetre
- informal short for thousand