Synonyms of the word 
THRIFTLESS → IMPROVIDENT
thriftless
- adj. wastefully reckless in the use of money or other resources.
improvident
- adj. failing to provide for the future; reckless.
- adj. incautious; prone to rashness.
If you are interested in words, visit the following sites :
- wiktionary.org/thriftless For complete definition of a word
- 1word.ws/thriftless to play with words, suffixs, prefixs, etc.