1. In a stupid manner
   - densely, obtusely 
2. In an inarticulate manner
   "I nodded dumbly and he slit the envelope"

See also: dumb

• mental dexterity
• mental disease
• mental disorder
• mental disturbance
• mental energy
• mental exhaustion
• mental faculty
• mental health
• mental home
• mental hospital
• mental hygiene
• mental illness
• mental image
• mental imagery
• mental institution
• mental lexicon
• mental measurement
• mental note
• mental object
• mental picture
• mental process
• mental quickness
• mental rejection
• mental representation
• mental reservation