Bear witness (to) is an expression that means to provide evidence or testimony in support of a fact or event. ATTEST and TESTIFY are two words that can be used to describe this action. ATTEST is a six-letter word meaning to affirm or declare to be true, while TESTIFY is a seven-letter word meaning to give evidence or to bear witness to something. Both words can be used to describe the act of providing evidence or testimony in support of a fact or event.