An enclosed and essentially self-sufficient (but not necessarily isolated) experimental environment or ecosystem that is on a larger scale than a laboratory microcosm.
Origin
1980s. From meso- + -cosm.
Definition of mesocosm in US English:
mesocosm
nounˈmɛsə(ʊ)ˌkɒz(ə)m
Ecology
An enclosed and essentially self-sufficient (but not necessarily isolated) experimental environment or ecosystem that is on a larger scale than a laboratory microcosm.