amalgamate v.

1610s, "act of compounding mercury with another metal," noun of action from archaic amalgam (v.) "to alloy with mercury" (see amalgamate). The figurative, non-chemical sense of "a combining of different things into one uniform whole" is attested from 1775. Especially of the union or merger of corporations under one direction.

c. 1400, "a blend of mercury with another metal; soft mass formed by chemical manipulation," from Old French amalgame or directly from Medieval Latin amalgama, "alloy of mercury (especially with gold or silver)," c. 1300, an alchemists' word, probably from Arabic al-malgham "an emollient poultice or unguent for sores (especially warm)" [Francis Johnson, "A Dictionary of Persian, Arabic, and English"], which is itself perhaps from Greek malagma "softening substance," from malassein "to soften," from malakos "soft" (from PIE *meldh-, from root *mel- (1) "soft"). The figurative meaning "compound of different things" is from 1790.

1590s, "reduce to a soft mass by combination with mercury," from amalgam + -ize. Related: Amalgamized; amalgamizing.