The bristol chart is commonly used for describing the texture and consistency of stools. See chart and details below.
By Cabot Health, Bristol Stool Chart (http://cdn.intechopen.com/pdfs-wm/46082.pdf) [CC BY-SA 3.0], via Wikimedia Commons
Quoting the wikipedia article linked above
The seven types of stool are:
- Separate hard lumps, like nuts (hard to pass)
- Sausage-shaped, but lumpy
- Like a sausage but with cracks on its surface
- Like a sausage or snake, smooth and soft
- Soft blobs with clear cut edges (passed easily)
- Fluffy pieces with ragged edges, a mushy stool
- Watery, no solid pieces, entirely liquid
Types 1 and 2 indicate constipation, with 3 and 4 being the ideal stools
(especially the latter), as they are easy to defecate while not
containing excess liquid, and 5, 6 and 7 tending towards diarrhoea.