Covered with or containing mold: moldy bread. (adjective)
Musty or stale, as from age or decay.(adjective)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "moldy" in a sentence
"Mortified by the prospect of salvaging a king's ransom in moldy books and horrified by word that repulsive local nobleman Lord Laphroig seeks to marry her Mistaya decides that the only way to run her own life is to run away from home."
"But his short stories are available only in moldy old paperbacks or expensive small-press books, and I don't think he's read much these days, which is a huge shame."
"Another method is to grind the water lilies into a pulp, put them in a pile, keep them moist, and let them get moldy -- in other words -- compost them for a week."