Runt

noun

1. The smallest animal of a litter.
2. (by extension) The smallest child in the family.

   "the runt of the family"

3. Undersized or stunted plant, animal or person.
4. An Ethernet packet that does not meet the medium's minimum packet size of 64 bytes.
5. A single word (or portion of a hyphenated word) that appears as the last line of a paragraph.