back up (v.)

• advance
• affirm
• ascend
• attest
• authenticate
• back
• backpedal
• backtrack
• bear
• bolster
• brace
• budge
• buttress
• carry
• certify
• champion
• change
• circle
• circumstantiate
• climb
• commission
• confirm
• corroborate
• countermarch
• cradle
• cushion
• deputize
• descend
• document
• ebb
• elect
• endorse
• flow
• follow
• fortify
• go
• gyrate
• hold
• maintain
• mount
• move
• nominate
• pillow
• plunge
• probate
• progress
• prop
• prove
• ratify
• regress
• reinforce
• represent
• retrogress
• reverse
• revert
• rise
• rotate
• run
• second
• shift
• shore
• shoulder
• sink
• soar
• spin
• stay
• stir
• stream
• strengthen
• subside
• subsidize
• substantiate
• subvention
• support
• sustain
• trail
• travel
• undergird
• underlie
• underpin
• understudy
• uphold
• validate
• verify
• vote
• wane
• warrant
• whirl