I. ˈbōl-stər noun
Etymology: Middle English, from Old English; akin to Old English belg bag — more at belly
Date: before 12th century
1. : a long pillow or cushion
2. : a structural part designed to eliminate friction or provide support or bearing
II. transitive verb
( bol·stered ; bol·ster·ing -st(ə-)riŋ)
Date: 15th century
1. : to support with or as if with a bolster : reinforce
2. : to give a boost to
news that bolster ed his spirits
• bol·ster·er -stər-ər noun