Noun, pl. dissections
1. The process of disassembling and observing something to determine its internal structure and as an aid to discerning the functions and relationships of its components. (wikipedia.org)
2. The action of dissecting a body or plant to study its internal parts. (Google Dictionary)
3. Cutting so as to separate into pieces. (wordnetweb.princeton.edu)
4. Anything dissected; especially, some part, or the whole, of an animal or plant dissected so as to exhibit the structure; an anatomical so prepared. Dissection wound, a poisoned wound incurred during the dissection of a dead body. (biology-online.org)
Word origin: Latin disssecare = to cut up, from dis = apart, sectum = cut (c.f. anatomy).