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

Encyclopedia: Hmm

• construction worker
• constructional
• constructionist
• constructive
• constructive breach
• constructive eviction
• constructive fraud
• constructive metabolism
• constructive possession
• constructive trust
• constructive-metabolic
• constructively
• constructiveness
• constructivism
• constructivist
• constructor
• construe
• construe with
• consubstantial
• consubstantiate
• consubstantiation
• consuetude
• consuetudinal
• consuetudinary
• consul