association - noun

a formal organization of people or groups of people

the act of consorting with or joining with others

the state of being connected together as in memory or imagination

the process of bringing ideas or events together in memory or imagination

a social or business relationship

a relation resulting from interaction or dependence

(chemistry) any process of combination (especially in solution) that depends on relatively weak chemical bonding

(ecology) a group of organisms (plants and animals) that live together in a certain geographical region and constitute a community with a few dominant species

association - thesaurus

affiliation   connection   connexion   tie