straggler

Short definition from Wiktionary

Noun

1. 1
   Someone who goes against the direct or proper course, or from the company to which they belong.
2. 2
   One who falls behind the rest, for example in a race.
3. 3
   One who roams without any settled direction.
4. 4
   A migratory animal found away from its usual range.
5. 5
   A roving vagabond.
6. 6
   Something that shoots, or spreads out, beyond the rest, or too far; an exuberant growth.
7. 7
   Something that stands alone or by itself.