As nouns the difference between thriftiness and unthrift
is that thriftiness is the property of being thrifty while unthrift is a lack of thriftiness; prodigality.
As an adjective unthrift is
unthrifty.
thriftiness
English
Noun
(-)
The property of being thrifty.
Synonyms
* frugality
* parsimony
unthrift
English
Noun
(
en noun)
A lack of thriftiness; prodigality.
Someone who is not thrifty; a spendthrift, someone who is not careful with their money.
*1633 , John Donne, "The Autumnall":
*:But name not Winter-faces , whose skin's slacke; / Lanke, as an unthrifts purse [...].