WordWeb Online

1. Made to seem smaller or less (especially in worth)
   - diminished, small

1. Cause to seem less serious; play down
   "Don't belittle his influence"
   - minimize, denigrate, derogate, minimise [Brit]
    
2. Express a negative opinion of
   - disparage, pick at
    
3. Lessen the authority, dignity, or reputation of
   "don't belittle your colleagues"
   - diminish

See also: decreased, reduced

Type of: criticise [Brit], criticize, decrease, knock, lessen, minify, pick apart