Assimilations meaning : The act of assimilating or the state of being assimilated. The metabolic conversion of nutrients into tissue. (by extension) The absorption of new ideas into an existing cognitive structure. A sound change process by which the phonetics of a speech segment becomes more like that of another segment in a word (or at a word boundary), so that a change of phoneme occurs. (cultural studies) The adoption, by a minority group, of the customs and attitudes of the dominant culture.