<p><strong>noun</strong></p><ul><li>A substance, as oil or grease, for lessening friction, especially in the working parts of a mechanism.</li></ul><p><strong>verb</strong></p><ul><li>(used with object) To make fat.</li><li>To feed (animals) abundantly before slaughter.</li><li>To enrich: to fatten the soil; to fatten one's pocketbook.</li><li>Cards. Poker: To increase the number of chips in (a pot).</li><li>Pinochle: To play a card that scores high on (a trick) expected to be taken by a partner.</li></ul><p><strong>adjective</strong></p><ul><li>Capable of lubricating; used to lubricate.</li></ul>