One who knowingly makes a decision or takes action that is to his/her own disadvantage.

A person who lives an admirably holy but eccentric life, at odds with conventional lifestyles.

(idiomatic) to waste, squander

Court jester; jester.

plural of fool's mate

(archaic, intransitive) To act foolishly.

(colloquial, transitive) to trick/fool somebody

Having the heart of a fool; foolish.

Aethusa cynapium, an annual umbelliferous plant that resembles parsley but is poisonous.

(derogatory, slang) One who uses fossil fuels without concern for their environmental impact.