Etymology
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firm (v.)

c. 1300, fermen "make firm, establish," from Old French fermer "consolidate; fasten, secure; build, set up; fortify" (12c.) or directly from Latin firmare "make firm; affirm; strengthen, fortify, sustain; establish, prove, declare," from firmus "strong, steadfast, stable" (see firm (adj.)). Intransitive use, "become firm" is from 1879; with up (adv.) from 1956. Related: Firmed; firming.

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firm (adj.)

late 14c., ferm, "strong, steady" (of things), "permanent, enduring" (of agreements), "steadfast, steady" (of persons), "sound, well-founded" (of arguments), from Old French ferm "strong, vigorous; healthy, sound; steadfast, loyal, faithful" (12c.), from Latin firmus "strong, steadfast, enduring, stable," figuratively "constant, steadfast, trusty, faithful," from suffixed form of PIE root *dher- "to hold firmly, support." The spelling return to -i- in late 1500s was modeled on Latin. Related: Firmly; firmness.

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firm (n.)

"business house," 1744, according to Barnhart from German Firma "a business, name of a business," originally "signature," from Italian firma "signature," from firmare "to sign," from Latin firmare "make firm, affirm," in Late Latin, "confirm (by signature)," from firmus "strong; stable," figuratively "constant, trusty" (see firm (adj.)).

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firmware (n.)

"permanent software programmed into a read-only memory and providing the low-level control for the device's hardware," 1968, from firm (adj.) + ending from software.

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*dher- 

Proto-Indo-European root meaning "to hold firmly, support." 

It forms all or part of: affirm; confirm; Darius; dharma; farm; fermata; firm (adj.); firm (n.); firmament; furl; infirm; infirmary; terra firma; throne.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit dharmah "custom, statute, law," dharayati "holds;" Prakrit dharaṇa "a holding firm;" Iranian dāra‑ "holding;" Greek thronos "seat;" Latin firmus "strong, steadfast, enduring, stable;" Lithuanian diržnas "strong;" Welsh dir "hard," Breton dir "steel."

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affirmation (n.)

early 15c., affirmacioun, "assertion that something is true," from Old French afermacion "confirmation" (14c.), from Latin affirmationem (nominative affirmatio) "an affirmation, solid assurance," noun of action from past-participle stem of affirmare "to make steady; strengthen; confirm," from ad "to" (see ad-) + firmare "strengthen, make firm," from firmus "strong" (see firm (adj.)).

In law, as the word for the conscientious-objector alternative to oath-taking (Quakers, Moravians, etc.), it is attested from 1690s; if false, it incurs the same penalty as perjury.

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affirmative (adj.)

"answering 'yes,' " mid-15c., from use in logic; from Old French affirmatif, earlier afirmatif (13c.), from Latin affirmativus, from affirmat-, past-participle stem of affirmare "to make steady; strengthen; confirm," from ad "to" (see ad-) + firmare "strengthen, make firm," from firmus "strong" (see firm (adj.)).

As a noun from early 15c., "that which affirms or asserts." American English affirmative action "positive or corrective effort by employers to prevent discrimination in hiring or promotion" is attested from 1935 with regard to labor unions (reinstatement of fired members, etc.). The specific racial sense is attested from 1961; by late 1970s the sense had shifted toward pro-active methods such as hiring quotas. Related: Affirmatively.

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terra firma (n.)

c. 1600, "part of the Italian mainland ruled by Venice," from Modern Latin terra firma, literally "firm land," from Latin terra "earth, land" (from PIE root *ters- "to dry") + firma, fem. of firmus "strong, steadfast" (from suffixed form of PIE root *dher- "to hold firmly, support"). Meaning "the land" (as distinct from "the sea") is first attested 1690s. Hakluyt and Sandys also used English firm (n.) to mean "the firm land, the mainland, terra firma."

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firmament (n.)

mid-13c., from Old French firmament or directly from Latin firmamentum "firmament," literally "a support, a strengthening," from firmus "strong, steadfast, enduring" (from suffixed form of PIE root *dher- "to hold firmly, support" ).

Used in Late Latin in the Vulgate to translate Greek stereoma "firm or solid structure," which translated Hebrew raqia, a word used of both the vault of the sky and the floor of the earth in the Old Testament, probably literally "expanse," from raqa "to spread out," but in Syriac meaning "to make firm or solid," hence the erroneous translation. Related: Firmamental.

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fasten (v.)

Old English fæstnian "make fast, make firm, fix, secure," also "ratify, betroth, confirm," from Proto-Germanic *fastinon "to make firm or fast" (source also of Old Frisian festnia "to make firm, bind fast," Old Saxon fastnon, Old High German fastnion, German festnen, Old Norse fastna "to pledge, betroth"), from PIE *fast "solid, firm" (see fast (adj.)). Related: Fastened; fastening.

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