substantiate

attest, authenticate, bear out, document, evidence, support, sustain, uphold

confirm, corroborate, justify, validate, verify

avouch, back (up), testify (to), vouch (for), witness

guarantee, warrant

affirm, assert, aver, avow, declare, profess

demonstrate, document, establish, prove, reinforce (also reenforce)

actualize, concretize, realize

exemplify, illustrate, image, objectify, symbolize, typify

back (up), buttress, corroborate

evidence, evince, record, support, uphold, witness

adduce, attest, authenticate, certify, identify

confirm, sustain, verify, vouch

clinch, nail, settle

confirm, establish, prove, verify

affirm, avouch, validate