1. in a rancid manner; with a stale, unpleasant smell or taste due to decomposition of fats or oils

Examples

• The butter had been left out too long and smelled rancidly.
• The old cooking oil tasted rancidly bitter.
• Fish left in the sun will smell rancidly within hours.
• The nuts had gone bad and tasted rancidly sour.
• The milk had turned and smelled rancidly offensive.