Pronunciation: (slen'dur),[key] —adj.,-er, -est. 1. having a circumference that is small in proportion to the height or length: a slender post. 2. thin or slight; light and graceful: slender youths. 3. small in size, amount, extent, etc.; meager: a slender income. 4. having little value, force, or justification: slender prospects. 5. thin or weak, as sound.