1. used to express thought, consideration, or mild doubt while pausing to think
Usage: informal; often spelled with varying numbers of m's (hm, hmm, hmmm, hmmmm)
2. used to express interest, curiosity, or skepticism about something said
Usage: informal

Examples

• Hmmm, I'm not sure I agree with that.
• She said hmmm and then took a moment to think before answering.
• Hmmm, that's a good point I hadn't considered.
• He looked at the puzzle and said hmmm while scratching his head.
• Hmmm, something doesn't seem right about this explanation.
• The teacher paused and said hmmm before asking the next question.