"The relation which is commutative and connected" (J. FEIBLEMAN & J.W. FRIEND, 1969, p.33)
Grains of sand which accumulate in a dune are related in an associative way, since this way is commutative (The order in which they accumulate is irrelevant), and connective (since no element needs of any intermediary one to be in contact)
Association is thus a simple, non-structural and non- functional relation, at least in the meaning proposed by FEIBLEMAN and FRIEND It is here the most primitive and rudimentary form of coordination among elements.
It reflects however a trend, generally induced by common conditions imposed to the elements by the environment, as for example dominant winds on sand dunes.
The generally accepted sense in social psychology and sociology goes quite farther than this and includes the results of closeness, i.e. defined interactions in groups and social systems.