The occurrence of two different or opposing things in the same time and place.
A close, prolonged association between two or more organisms of different species, regardless of benefit to the members.
A close, prolonged association between two or more organisms of different species that normally benefits both members. An interspecies cooperation.
The state of people of different types, races, cultures, communities, etc., living together.
A relationship of mutual benefit, especially among different species.
A temporal relationship between events.
The tabular arrangement of contemporary events etc. in history.
The state of being synchronous.