forge (n.)

late 14c., "a smithy," from Old French forge "forge, smithy" (12c.), earlier faverge, from Latin fabrica "workshop, smith's shop," hence also "a trade, an industry;" also "a skillful production, a crafty device," from faber (genitive fabri) "workman in hard materials, smith" (see fabric).

As the word for the heating apparatus itself (a furnace fitted with a bellows), from late 15c. Forge-water (1725), in which heated iron has been dipped, was used popularly as a medicine in 18c.

early 14c., "to counterfeit" (a letter, seal, document, etc.), from Old French forgier "to forge, work (metal); shape, fashion; build, construct; falsify" (12c., Modern French forger), from Latin fabricari "to frame, construct, build," from fabrica "workshop" (see forge (n.)).

The literal meaning "to form (something) by heating in a forge and hammering" is from late 14c. in English.

The word also was used in Middle English of the minting of coins, so that by late 14c. it meant "issue good money." But it is attested earlier in the sense of "fabricate by false imitation," and by mid-14c. it was used in a general sense of "to plot, contrive":

They wol forge a long tale and peynten it with alle circumstaunces. [Chaucer, Parson's Tale]

It was extended to "issue spurious (paper) money" in modern times. Related: Forged; forging.

1769 (with an apparent isolated use from 1610s), "make way; move ahead slowly, with difficulty, or by mere momentum," a word of unknown origin, perhaps an alteration of force (v.), but perhaps rather from forge (n.), via the notion of steady hammering at something. Originally and properly nautical, in reference to vessels, and in nautical use also transitive (with on or over).