unthrift

From un- +‎ thrift.

unthrift (countable and uncountable, plural unthrifts)

1. A lack of thriftiness; prodigality.
2. (now rare) Someone who is not thrifty; a spendthrift, someone who is not careful with their money.
   • 1609, William Shakespeare, Sonnet 9

     Look what an unthrift in the world doth spend ...

   • 1633, John Donne, "The Autumnall":

     But name not Winter-faces, whose skin's slacke;

     Lanke, as an unthrifts purse ...

unthrift (comparative more unthrift, superlative most unthrift)

1. Unthrifty.