The Collaborative International Dictionary of English v.0.48:
Confirm \Con*firm"\, v. t. [imp. & p. p. Confrmed; p. pr. &
vb. n. Confirming.] [OE. confermen, confirmen, OF.
confermer, F. confirmer, fr. L. confirmare; con- + firmare to
make firm, fr. firmus firm. See Firm.]
1. To make firm or firmer; to add strength to; to establish;
as, health is confirmed by exercise.
Confirm the crown to me and to mine heirs. --Shak.
And confirmed the same unto Jacob for a law. --Ps.
2. To strengthen in judgment or purpose.
Confirmed, then, I resolve
Adam shall share with me in bliss or woe. --Milton.
3. To give new assurance of the truth of; to render certain;
to verify; to corroborate; as, to confirm a rumor.
Your eyes shall witness and confirm my tale. --Pope.
These likelihoods confirm her flight. --Shak.
4. To render valid by formal assent; to complete by a
necessary sanction; to ratify; as, to confirm the
appoinment of an official; the Senate confirms a treaty.
That treaty so prejudicial ought to have been
remitted rather than confimed. --Swift.
5. (Eccl.) To administer the rite of confirmation to. See
Those which are thus confirmed are thereby supposed
to be fit for admission to the sacrament. --Hammond.
Syn: To strengthen; corroborate; substantiate; establish;
fix; ratify; settle; verify; assure.
Moby Thesaurus II by Grady Ward, 1.0:
204 Moby Thesaurus words for "confirm":
OK, accede, accept, acclimate, acclimatize, accommodate, accredit,
accustom, acquiesce, adapt, addict, adjust,
administer the Eucharist, affirm, amen, anoint, approve, assay,
assent, assure, attest, audit, authenticate, authorize, autograph,
back, back up, be sponsor for, bear out, bed, beef up, bind,
bolster, bond, brace, brace up, break, break in, bring to test,
buttress, case harden, certify, check, check and doublecheck,
check out, check over, chrism, circumstantiate, clinch, collate,
condition, consent, corroborate, cosign, countersecure,
countersign, cross-check, cut and try, deep-dye, define, do duty,
document, domesticate, domesticize, double-check, embed, encourage,
endorse, engraft, engrave, ensure, entrench, essay, establish,
etch, experiment, familiarize, fix, fortify, found, gentle, gird,
give a try, give a tryout, give permission, give the go-ahead,
give the imprimatur, give thumbs up, ground, guarantee, guaranty,
habituate, harden, have a go, housebreak, impact, implant, impose,
impress, imprint, infix, ingrain, initial, inscribe, insure, inure,
invigorate, jam, justify, lay hands on, lodge, make good, minister,
naturalize, nerve, notarize, officiate, orient, orientate, pack,
painstakingly match, pass, pass on, pass upon, perform a rite,
perform service, permit, plant, play around with, practice upon,
print, probate, prop, prove, put to trial, ratify, recheck,
recognize, refresh, reinforce, reinvigorate, research,
restrengthen, road-test, root, rubber stamp, run a sample, sample,
sanction, say amen to, scrutinize comparatively, seal, season,
seat, second, secure, set, set in, settle, shake down, shore up,
sign, sign and seal, sign for, sponsor, stamp, stand behind,
stand up for, steel, stereotype, stiffen, strengthen, subscribe,
subscribe to, substantiate, support, sustain, swear and affirm,
swear to, take to, tame, taste, temper, test, toughen, train,
triple-check, try, try it on, try out, undergird, underpin,
undersign, underwrite, uphold, validate, verify, visa, vise, vouch,
warrant, wedge, witness, wont