witness

[1]	see , observe , watch , look on/at , view , behold , mark , note , notice , take in , (Colloq) spot , catch
[2]	countersign , sign , certify , endorse , substantiate , document , certificate
[3]	find , see

[1]	observer , witnesser , informant , onlooker , spectator , viewer , eyewitness , bystander , watcher , (Rare) earwitness
[2]	deponent , spectator , viewer , testifier , corroborating witness , watcher , looker , corroborator
[3]	bear witness (to/of) , testify (to) , attest (to) , be/give/provide/furnish/constitute evidence/proof/testimony (of/to) , verify , confirm , corroborate , show , prove
[4]	attestant , attestor , attestator