1) to prove beyond doubt the origin etc of (something) (authenticate)
2) to supply proof of (something); show (something) beyond doubt to be true (prove)
by general agreement; as is agreed
without a doubt
so as to be easily understood
without any doubt
in fact; without doubt; (used to express interest, surprise, protest etc)
without a doubt
(used to express difficulty in believing) if experience or probability can be trusted
without doubt
sincerely; genuinely; certainly
really, doubtlessly
undoubtedly true
definite, proven
