Someone who is not thrifty; a spendthrift, someone who is not careful with their money.(noun)
Unthrifty.(adjective)
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Use "unthrift" in a sentence
"The New Bedford superintendent of schools argued that it was the lack of sewing skills that caused what he saw to be the "unthrift and ragged shiftlessness of many homes.""
"The Earl of Oxford, a young unthrift, whom Foster had more than once accommodated with loans on usurious interest, acknowledged, on this appeal, that he knew him as a wealthy and independent franklin, supposed to be worth much money, and verified the certificate produced to be his handwriting."
"He had always disliked Owen, regarding him as an unthrift, any close connexion with whom could only bring contamination on the Fitzgerald property; and Owen had returned the feeling tenfold."