Association(noun)
1.an organization of people with a common purpose and having a formal structure.
2.the act of associating or state of being associated.
3.friendship; companion ship:Their close association did not last long.
4.connection or combination.
5.the connection or relation of ideas, feelings, sensations, etc .; correlation of elements of perception, reasoning, or the like.
6.an idea, image, feeling, etc., suggested by or connected with something other than itself; an accompanying thought, emotion, or the like; an overtone or connotation : My associations with that painting are of spring like days.
7.Ecology. a group of plants of one or more species living together under uniform environmental conditions and having a uniform and distinctive aspect.