Meaning

noun a pillow that is often put across a bed underneath the regular pillows

verb support and strengthen

verb prop up with a pillow or bolster

originFrom Middle English bolster, bolstre, from Old English bolster (“pillow”), from Proto-West Germanic *bolstr, from Proto-Germanic *bulstraz (“pillow, cushion”). Cognate with Scots bowster (“bolster”), West Frisian bulster (“mattress”), Dutch bolster (“husk, shell”), German Polster (“bolster, pillow, pad”), Swedish bolster (“soft mattress, bolster”), Icelandic bólstur (“pillow”).

Etymology from Wiktionary, CC BY-SA 3.0