bolster
BOHL-sterverbMeaning to support or strengthen
Memory hook a BOLSTER is a propping PILLOW. Granny Mae keeps slumping on the bed until Rosa props her up with a long, firm pillow called a bolster. To prop up and support something is to bolster it.
Winning the first game bolstered the team’s confidence.
In context Her argument was weak on its own, so she bolstered it with three surveys and a letter from the town engineer.
Similar strengthen, support, reinforce, boost
Opposite weaken, undermine
From bolster, an old word for a long, firm pillow used to prop things up.