mid-13c., confirmyn, confermen "to ratify, sanction, make valid by a legal act," from Old French confermer (13c., Modern French confirmer) "strengthen, establish, consolidate; affirm by proof or evidence; anoint (a king)," from Latin confirmare "make firm, strengthen, establish," from assimilated form of com"together," but here perhaps an intensive prefix (see con-), + firmare "to strengthen," from firmus "strong, steadfast" (from suffixed form of PIE root *dher- "to hold firmly, support").
From mid-14c. as "make firm or more firm, add strength to;" late 14c. as "make certain or sure, give an assurance of truth, verify." Related: Confirmative; confirmatory.
late 14c., of diseases, "firmly established," past-participle adjective from confirm. From mid-15c. as "supported by authority or proof." Of persons, "established in the habit, inveterate," from 1826.
c. 1300, confyrmacyoun, the rite whereby baptized persons are admitted to full communion with the Church, from Old French confirmacion (13c.) "strengthening, confirmation; proof; ratification," and directly from Latin confirmationem (nominative confirmatio) "a securing, establishing; an assurance, encouragement," noun of action from past-participle stem of confirmare (see confirm).
Meaning "verification, proof, supporting evidence" is from late 14c. Meaning "act of rendering valid by formal assent of authority" is from c. 1400; sense of "action of making sure, a rendering certain or proving to be true" from early 15c.
Proto-Indo-European root meaning "to hold firmly, support."
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."
1590s, "bear witness to, officially confirm; give proof or evidence of," from French attester (Old French atester, 13c.) "affirm, bear witness to," from Latin attestari "confirm, prove," literally "bear witness to," from assimilated form of ad "to" (see ad-) + testari "bear witness," from testis "witness" (see testament). Related: Attested; attesting.
mid-14c., ratifien, "confirm, approve, sanction, validate by formal act of approval," from Old French ratifier (13c.), from Medieval Latin ratificare "confirm, approve," literally "fix by reckoning," from Latin ratus "fixed by calculation; determined; approved; certain, sure; valid" (past-participle adjective from reri "to reckon, think;" from PIE root *re- "to reason, count") + combining form of facere "to make" (from PIE root *dhe- "to set, put"). Related: Ratified; ratifying.
Middle English affermen, affirmen, "to decide upon" (c. 1300); "to state positively" (late 14c.), from Old French afermer (Modern French affirmer) "affirm, confirm; strengthen, consolidate," from Latin affirmare "to make steady, strengthen," figuratively "confirm, corroborate," from ad "to" (see ad-) + firmare "strengthen, make firm," from firmus "strong" (from suffixed form of PIE root *dher- "to hold firmly, support").
The spelling was refashioned 16c. in French and English on Latin model. Legal sense "declare solemnly (as before a court) but without an oath" is from early 15c. Related: Affirmed; affirming.
mid-15c., attestacion, "testimony, a document embodying testimony," from Latin attestationem (nominative attestatio) "an attesting, testimony," noun of action from past-participle stem of attestari "to prove, confirm" (see attest). From 1670s as "a declaration in support of a fact."