WordWeb Online

1. Becoming smaller, less or appearing to do so
   "diminishing returns"; "his diminishing respect for her"

1. Become smaller or less in size, extent, or range
   "The amount of homework diminished towards the end of the semester";
   - decrease, lessen, fall
    
2. Lessen the authority, dignity, or reputation of
   "don't diminish your colleagues";
   - belittle

See also: decreasing

Type of: change magnitude, decrease, lessen, minify

Antonym: increase