undergird (v.)

• affirm
• attest
• authenticate
• back
• bear
• bolster
• brace
• buttress
• carry
• certify
• circumstantiate
• confirm
• corroborate
• cradle
• cushion
• document
• finance
• fortify
• fund
• gird
• harden
• hold
• invigorate
• keep
• maintain
• nerve
• pillow
• probate
• prop
• prove
• ratify
• refresh
• reinforce
• reinvigorate
• restrengthen
• shore
• shoulder
• stay
• steel
• stiffen
• strengthen
• subsidize
• substantiate
• subvention
• support
• sustain
• temper
• toughen
• underlie
• underpin
• uphold
• validate
• verify
• warrant