To keep from yielding or failing during stress or difficulty
Our internet was so slow we had to get an extender in order to bolster our poor home wi-fi.
Her presence would bolster his weak will.
Deidre fled to it, needing something to bolster the defenses that were dropping too fast.
We would need to recall the armies from the south to bolster our numbers.
Prince Andrew answered all his questions reluctantly but reasonably, and then said he wanted a bolster placed under him as he was uncomfortable and in great pain.