Synonyms for Act as a witness:

• v.

  •give assurance (verb)
  • vouch.
  •vouch (verb)
  • say so,
  • be responsible for,
  • swear to,
  • stand up for,
  • bear testimony,
  • support,
  • rubber-stamp,
  • contend,
  • sign for,
  • attest to,
  • swear up and down.

• Other synonyms:

  •Other relevant words:
  • abide,
  • accompaniment,
  • account,
  • actualise,
  • actualize,
  • adjudge,
  • affirm,
  • alright,
  • announce,
  • answer for,
  • approve,
  • argue,
  • ascertain,
  • assert,
  • asseverate,
  • assure,
  • attest,
  • attestant,
  • attestator,
  • attestor,
  • aver,
  • avert,
  • avoid,
  • avouch,
  • avow,
  • back,
  • back up,
  • backbone,
  • backing,
  • backrest,
  • backup,
  • backward,
  • backwards,
  • bear,
  • bear on,
  • bear out,
  • bear witness,
  • bet on,
  • binding,
  • body forth,
  • book binding,
  • bread and butter,
  • brook,
  • buy at,
  • carry on,
  • certify,
  • check,
  • co-sign,
  • compete,
  • concede,
  • confess,
  • confirm,
  • connote,
  • consecrate,
  • conserve,
  • contest,
  • continue,
  • control,
  • cool,
  • cope,
  • corroborate,
  • cosign,
  • countenance,
  • cover,
  • deal,
  • debar,
  • debate,
  • declare,
  • defend,
  • deflect,
  • demonstrate,
  • digest,
  • documentation,
  • dorsum,
  • drag,
  • drop back,
  • drop behind,
  • embody,
  • endorse,
  • endorsement,
  • endure,
  • ensure,
  • essay,
  • establish,
  • evidence,
  • examine,
  • exert,
  • fence,
  • fend for,
  • fend off,
  • fight,
  • financial backing,
  • financial support,
  • find,
  • fine,
  • frequent,
  • funding,
  • gage,
  • game,
  • get behind,
  • get by,
  • grapple,
  • guarantee,
  • guaranty,
  • hang back,
  • head off,
  • hind,
  • hinder,
  • hold,
  • hold up,
  • hunky-dory,
  • imprimatur,
  • incarnate,
  • indorse,
  • informant,
  • insist,
  • insure,
  • keep,
  • keep going,
  • keep up,
  • leaven,
  • licence,
  • license,
  • livelihood,
  • living,
  • looker,
  • maintain,
  • make do,
  • make out,
  • manage,
  • manifest,
  • musical accompaniment,
  • observe,
  • obviate,
  • okay,
  • okeh,
  • okey,
  • patron,
  • patronage,
  • patronise,
  • patronize,
  • plump for,
  • plunk for,
  • postulate,
  • predicate,
  • presenter,
  • preserve,
  • pretend,
  • proclaim,
  • profess,
  • promise,
  • prove,
  • punt,
  • put forward,
  • rachis,
  • raise,
  • realise,
  • realize,
  • rear,
  • rearward,
  • rearwards,
  • reassert,
  • reassure,
  • reenforcement,
  • reinforcement,
  • repugn,
  • rise,
  • sanction,
  • second,
  • secure,
  • see,
  • see to it,
  • shew,
  • shop,
  • shop at,
  • show,
  • spectator,
  • spinal column,
  • spine,
  • sponsor,
  • stake,
  • stand,
  • stave off,
  • stick out,
  • stock warrant,
  • stock-purchase warrant,
  • stomach,
  • struggle,
  • subscribe,
  • substantiate,
  • suffer,
  • supporter,
  • supporting,
  • sustain,
  • sustenance,
  • swan,
  • swear,
  • take the stand,
  • tell,
  • test,
  • testify,
  • tolerate,
  • trail,
  • try,
  • try out,
  • turn away,
  • turn up,
  • underpin,
  • undertake,
  • uphold,
  • validate,
  • verb phrase,
  • verify,
  • vertebral column,
  • vie,
  • viewer,
  • vow,
  • ward off,
  • warrant,
  • warrantee,
  • warranty,
  • watcher,
  • wield,
  • witness,
  • witnesser,
  • turn out,
  • put up,
  • put forth,
  • ok,
  • all right,
  • give an affidavit.

Antonyms for Act as a witness:

• v.

  • vouch
    reject, disapprove, veto, break, discredit, desert, refute, disclaim, renounce, contradict, deny, condemn, repudiate, discourage, disprove, oppose, disavow, invalidate, refuse, neglect.