descender

Short definition from Wiktionary

Noun

1. 1
   A person or thing that descends.
2. 2
   The part of a letter or number that is drawn below the baseline (the bottom of most lowercase letters).
3. 3
   A letter that has such a portion, such as g, j, or in some fonts Q.
4. 4
   A cyclist who excels at fast descents.
5. 5
   A belay device used in rock climbing, or as a fire escape.