pillow, n. — Green’s Dictionary of Slang

pillow n.

[its padding]

(US) a boxing glove.

1885		Bulletin (Sydney) 18 Apr. 14/2: In the articles signed by Farnan’s representative small gloves are stipulated, but the Melbourne party [...] now want the show to come off with the ordinary pillows.
1894		Outing (N.Y.) XXIV 443/1: Piled on a little table were four as dirty and badly-stained ‘pillows’ as I had ever set eyes on [DA].
1901		Sydney Sportsman (Surrey Hills, NSW) 6 Nov. 1/4: Naturally the boxers kicked about using ‘pillows’ and after the fifth round Denny declined to proceed.
1906		S. Ford Shorty McCabe 109: I was a little riled by that time [...] I offered to tie pillows on both hands and take ’em all three at once.

SE in slang uses

In compounds

pillowcase (n.) [play on horsefeathers n.]

(US) one who talks nonsense.

1922

Edwardsville Intelligencer (IL) 14 Sept. 4/4: The Flappers’ Dictionary [...] Pillow Case: Young man who is full of feathers.

pillow-mate (n.) [note Hindley, The Old Book Collector’s Miscellany (1873) ‘Serving [...] as a little Side Pillow, to render the Yoke of Matrimony more easy’]

a prostitute.

1890–1904

Farmer & Henley Sl. and Its Analogues.

pillow pigeons (n.)

(US black) bedbugs.

1942		Pittsburgh Courier (PA) 22 Aug. 7/6: Pillow pigeons — (bed bugs).
c.1943		‘Bill O. Lading’ You Chirped a Chinful!! n.p.: Pillow pigeons: Bed bugs.