kay vs thou

kay

• A thousand of some unit (from kilo-). 

• A kilometer. 

• The name of the Latin-script letter K. 

thou

• A unit of length equal to one-thousandth of an inch (25.4 µm). 

• A thousand, especially a thousand of some currency (dollars, pounds sterling, etc.). 

• To use the word thou. 

• To address (a person) using the pronoun thou, especially as an expression of contempt or familiarity.