bolster(noun, verb) noun1. a pillow that is often put across a bed underneath the regular pillowsDefinition categories: man–made, pillow verb1. support and strengthen- bolster moraleDefinition categories: change, reenforce, reinforce2. prop up with a pillow or bolsterDefinition categories: contact, prop, shore3. add padding toSimilar word(s): padDefinition categories: change, fill