Synonyms for Spendthrift (same or very similar meaning)
WordNet sense 1 (someone who spends money prodigally):
spender, scattergood, spend-allWordNet sense 2 (recklessly wasteful):
extravagant, prodigal, profligateWordNet sense 3 (tending to squander and waste):
wastefulFrom the ODE community, based on WordNetadd/edit