bolster.
1. Baluster-side.

2. Bellied profile of a pulvinated frieze.

3. Bolster-, cushion-, or pillow-work refers to rusticated masonry, each course of which is bowed out, as in Roman aqueduct-piers.

4. Timber corbel or plate supporting a truss, etc.

bol·ster / ˈbōlstər/ • n. (also bolster pillow) a long, thick pillow that is placed under other pillows for support. ∎  a part of a vehicle or tool providing structural support.• v. [tr.] support or strengthen; prop up: the fall in interest rates is starting to bolster confidence he wished to bolster up his theories with hard data. ∎  provide (a seat) with padded support: [as adj.] (bolstered) I snuggled down into the heavily bolstered seat.

bolster OE. bolster pillow, cushion = (M)Du. bolster, OHG. bolstar (G. polster), ON. bolstr :- Gmc. *bolstraz. perh. for *bolχstraz, f. *belʒ- swell (Cf. BELLY).
Hence bolster vb. (chiefly fig.) prop up XVI.