I recently came across the word "profligacy" in: "America needs a leader who will challenge this culture of 'profligacy.'" In this context "profligacy" means "recklessly wasteful." Yet, "profligation" means "to defeat or overthrow." They seem to come from the same word, "profligatus," Latin for "to ruin or to cast down." How did recklessly wasteful become a definition? Or, are they from different roots?

I'd never heard of "profligation" before. I see from a search on "profligate" at Dictionary.com that Webster's gives two definitions:

quote:

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1, Overthrown; beaten; conquered. [Obs.]
2. Broken down in respect of rectitude, principle, virtue, or decency; openly and shamelessly immoral or vicious; dissolute; as, profligate man or wretch.

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As you say, it comes from the Latin profligatus, past participle of profligare to strike or dash to the ground, to destroy.

It seems that the now obsolete original meaning changed somewhat in that the emphasis on being "broken down" became less. Nowadays its meaning seems to have narrowed somewhat from general dissolution to reckless overspending or being particularly wasteful.