To furnish proof of, to show.
1667: round he throws his baleful eyes / That witness'd huge affliction and dismay — John Milton, Paradise Lost, Book 1 ll. 56-7
To take as evidence.
To see or gain knowledge of through experience.
He witnessed the accident.
(construed with to or for) To present personal religious testimony; to preach at (someone) or on behalf of.
To see the execution of (a legal instrument), and subscribe it for the purpose of establishing its authenticity.
to witness a bond or a deed