early 15c., "act of assimilating," in reference to the body's use of nutrition, from Old French assimilacion, from Latin assimilationem (nominative assimilatio) "likeness, similarity," noun of action from past-participle stem of assimilare "to make like" (see assimilate).
The meaning "process of becoming alike or identical, conversion into a similar substance" is from 1620s. The figurative use is from 1790. The psychological sense is from 1855.
also mal-assimilation, "faulty digestion, imperfect nutrition," 1840, from mal- + assimilation.
"one who advocates racial or ethnic integration," 1900, originally in reference to Hawaii and possessions obtained by the U.S. in the war against Spain; later with reference to Jews in European nations; see assimilation + -ist. In Portuguese, assimilado (literally "assimilated," past participle of assimilar) was used as a noun of natives of the Portuguese colonies in Africa who were admitted to equal rights and citizenship.
"characterized by assimilation; capable of assimilating or of causing assimilation," 1520s; see assimilate + -ive. Alternative assimilatory is from 1775.
"a making human or humane; assimilation to humanity," 1753, also humanisation, noun of action from humanize.
before vowels quinqu-, word-forming element from classical Latin meaning "five, consisting of or having five," from Latin quinque "five" (by assimilation from PIE root *penkwe- "five").
1887 (transitive) "to subject to metabolism, transform by assimilation or decomposition;" 1934 (intransitive) "to perform metabolism;" from Greek metabole "a change" (see metabolism) + -ize. Related: Metabolized; metabolizing.
1590s, "a swallowing up" (now obsolete), from Latin absorptionem (nominative absorptio) "a swallowing," noun of action from past-participle stem of absorbere "swallow up" (see absorb). From 1714 specifically of "disappearance by assimilation into something else."
