1. past tense and past participle of hum; made a low continuous sound
2. sang a tune with closed lips, making a continuous musical sound
3. was busy with activity; operated smoothly and efficiently
Usage: informal

Examples

• The air conditioner hummed quietly in the background.
• She hummed her favorite song while cooking dinner.
• The bees hummed as they moved from flower to flower.
• He hummed a tune he couldn’t quite remember.
• The factory hummed with activity during the busy season.
• The computer hummed softly as it processed the data.
• She hummed contentedly while reading her book.