a cushion to support the head of a sleeping person
"After a long day, I rested my head on the soft pillow while drifting into sleep."
A soft cushion used to support the head in bed.
"She pulled the fluffy pillow up to her chin before drifting off to sleep."
In plain English: A pillow is a soft cushion you put under your head to sleep comfortably.
"She slipped under her soft pillow to get some rest before bed."
Usage: Use "pillow" as a countable noun, such as one pillow or two pillows, rather than an uncountable mass like some other bedding items. While you can place your hand on it for comfort while awake, its primary function is specifically to support the head during sleep.
A surname.
"Captain Pillow ordered his crew to change the course immediately."
From Middle English pilwe, from Old English pyle, pylu ("pillow"), from Proto-West Germanic *pulwī ("pillow"), from Latin pulvīnus ("cushion"), derived from pulvis ("dust, powder") + -īnus ("-ine"), for the filler of a pillow. Doublet of pulvinus. Cognate with Saterland Frisian Peel ("pillow"), Alemannic German Pfulme ("pillow"), Dutch peluw ("a long, narrow pillow"), German Pfühl ("a big and soft pillow"), German Low German Pöhl ("pad, pillow, cushion").