1. To provide an object or structure with physical support or reinforcement. A noun or pronoun can be used between "buttress" and "up." We need to buttress up that painting with another nail before it falls off the wall. I used a wood block to buttress the window up—otherwise, it comes crashing down when you least expect it.

2. To provide something or someone with financial support. Unfortunately, I think this merger is the only way we can buttress up our failing company.