Bolster means to strengthen, support, reinforce, or uplift. There are various synonyms of bolster, depending on the context and usage. Some of the most common synonyms for bolster include prop up, back up, buoy up, brace, fortify, underpin, enhance, boost, uplift, encourage, sustain, maintain, and assist. These synonyms are often interchangeably used in sentences or phrases that denote the action of supporting or enhancing something. For instance, "the government's new policies will bolster the economy," means the policies will strengthen the economy. In summary, bolster has numerous synonyms that convey the same or similar meanings, and choosing the right one will depend on the specific context.