diminutive

Short definition from Wiktionary

Adjective

1. 1
   Very small.
2. 2
   Serving to diminish.
3. 3
   Of or pertaining to, or creating a word form expressing smallness, youth, unimportance, or endearment.

Noun

1. 1
   A word form expressing smallness, youth, unimportance, or endearment.