diminish in WordNet English dictionary

1. lessen the authority, dignity, or reputation of
   "don't belittle your colleagues"
   diminish  belittle 
   
2. decrease in size, extent, or range
   "The amount of homework decreased towards the end of the semester"; "The cabin pressure fell dramatically"; "her weight fell to under a hundred pounds"; "his voice fell to a whisper"
   decrease  diminish  lessen  fall