The Collaborative International Dictionary
dissipative \dis"si*pa*tive\ (d[i^]s"s[i^]*p[asl]*t[i^]v), a. Tending to dissipate.
Dissipative system (Mech.), an assumed system of matter and motions in which forces of friction and resistances of other kinds are introduced without regard to the heat or other molecular actions which they generate; -- opposed to conservative system.
A dissipative structure is a dissipative system that has a dynamical régime that is in some sense in a reproducible steady state. This reproducible steady state may be reached by natural evolution of the system, by artifice, or by a combination of these two.