crumb

Short definition from Wiktionary

Noun

1. 1
   A small piece which breaks off from baked food (such as cake, biscuit or bread).
2. 2
   A small piece of any other solid substance.
3. 3
   A bit, small amount.
4. 4
   Ellipsis of crumb rubber.
5. 5
   The soft internal portion of bread, surrounded by crust.
6. 6
   A mixture of sugar, cocoa and milk, used to make industrial chocolate.
7. 7
   A nobody; a worthless person.
8. 8
   A body louse (Pediculus humanus).

Verb

1. 1
   To cover with crumbs.
2. 2
   To break into crumbs or small pieces with the fingers; to crumble.

Proper noun

1. 1
   A surname.