Synonyms for Bolster:

n.

invigorate, toughen, strengthen, harden, intensify, stiffen, sharpen. help, sustain. artifact (noun)
long pillow.
bedclothes (noun)
bedspread, comforter, bedlinen, afghan, bedclothes, bedding, blanket, counterpane, canopy.
bolster (noun)
long pillow, bolster up, support, pad.
prop (noun)
hold up, sustain, reinforce.
support (noun)
backing, Underpinning, crutch.

v.

change (verb)
bolster up, pad.
help (verb)
prop, support, uphold, buttress, help, hold up, reinforce, sustain, strengthen.
support (verb)
hinge, uphold, underpin, back, buttress, support, prop.

Other synonyms:

intensify. invigorate, stiffen, sharpen. harden, toughen. strengthen. bedclothes
bedspread, comforter, bedlinen, afghan, bedclothes, bedding, blanket, counterpane, canopy.
buttress
reinforce.
pad
pad.
support
support.
Other relevant words:
counterpane, canopy, blanket, stiffen, bedlinen, bolster up, bedding, harden, help, reinforce, hold up, sustain, intensify, invigorate, comforter, bedspread, toughen, long pillow, bedclothes, sharpen, strengthen, pad.

Usage examples for bolster

  1. The cushion at the back is round like a bolster the cushions on the sides are flat. – A Holiday in the Happy Valley with Pen and Pencil by T. R. Swinburne
  2. The two brothers sat up on their bolster and stared into the darkness. – Journeys Through Bookland V2 by Charles H. Sylvester
  3. He had endeavoured to obtain a private interview with Mrs. Bolster before she could be seen by Matthew Round; but in this he had not succeeded. – Orley Farm by Anthony Trollope