before vowels ferr-, word-forming element indicating the presence of or derivation from iron, from Latin ferro-, combining form of ferrum "iron," which is of unknown origin. Possibly of Semitic origin, via Etruscan [Klein]; Watkins suggests "possibly borrowed (via Etruscan) from the same obscure source as OE bræs "brass." Also sometimes especially indicative of the presence of iron in the ferrous state; ferri- indicating iron in the ferric state.

"act of pressing and smoothing clothes with a heated flat-iron," 1725, verbal noun from iron (v.). Ironing-board attested from 1762.

1959, from the verbal phrase, from iron (v.) + on (adv.).

"fire-dog, one of the pair of metallic stands used to support wood burned on an open hearth," c. 1300, aundiren, from Old French andier "andiron," which is of unknown origin, perhaps from Gaulish *andero- "a young bull" (source also of Welsh anner "heifer"), which would make sense if they once had bull's heads cast onto them. Altered by influence of Middle English iren (see iron (n.)).

1660s, cast iron, from iron (n.) + cast (adj.) "made by melting and being left to harden in a mold" (1530s), past-participle adjective from cast (v.) in its sense "to throw something (in a particular way)," c. 1300, especially "form metal into a shape by pouring it molten" (1510s). From 1690s as an adjective, "made of cast-iron;" figurative sense of "inflexible, unyielding" is from 1830.

surname, from German Eisenhauer, literally "iron-cutter, iron-hewer," "perhaps based on Fr. Taillefer" [George F. Jones, "German-American Names," 3rd ed., 2006]. See iron (n.) + hew (v.).

"iron for smoothing," 1810, from flat (adj.) + iron (n.). Applied to triangular or wedge-shaped buildings from 1862.

1794, the name of a fire-protection device to be used in theaters, a literal iron curtain; see iron (n.) + curtain (n.).

The new and exquisitely beautiful theatre of Drury-lane has the peculiar contrivance of an iron-curtain to secure the audience from all danger, in case of fire on the stage. Miss Farren, in the occasional epilogue, delivered on opening this new theatre, pleasantly informs the spectators that, should flames burst out in the part appropriated to the representation, they may comfort themselves with thinking that nothing can be burnt but the scenery and the actors. [The Monthly Review, June 1794]

From 1819 in the figurative sense "impenetrable barrier." In reference to the Soviet occupation of Eastern Europe, famously coined by Winston Churchill March 5, 1946, in speech at Westminster College, Fulton, Missouri, but it had been used earlier in this context (for example by U.S. bureaucrat Allen W. Dulles at a meeting of the Council on Foreign Relations, Dec. 3, 1945). The phrase had been used in the sense of "barrier at the edge of the sphere of influence of the Soviet Union" from 1920. During World War II, Goebbels used it in German (ein eiserner Vorhang) in the same sense. But its popular use in the U.S. dates from Churchill's speech.

late 14c., from iron (n.) + bound (adj.1). Figurative use from 1807.

1852 of knights, 1861, of warships, American English, from iron (n.) + clad. Figuratively, of contracts, etc., "very rigid or strict, allowing no evasion or escape," from 1884. As a noun meaning "iron-clad ship," it is attested from 1862.