1. Gentle utterance use to call someone's attention
   - ahem, hem 
2. Exclamation expressing doubt, deliberation, dissent, or hesitation
   - hum, ahem

Encyclopedia: Hmm

• snootiness
• snooty
• snooze
• snooze button
• snoozer
• snore
• snorer
• snoring
• snorkel
• snorkel breather
• snorkel diving
• snorkeler
• snorkeling
• snorkeller
• snorkelling
• snort
• snorter
• snorting
• snorty
• snot
• snot-nosed
• snotty
• snotty-nosed
• snout
• snout beetle