sleeper

noun

sleep·​er ˈslē-pər 

1

: one that sleeps

2

: a piece of timber, stone, or steel on or near the ground to support a superstructure, keep railroad rails in place, or receive floor joists : stringpiece

3

: sleeping car

4

: someone or something unpromising or unnoticed that suddenly attains prominence or value

the low-budget film became the summer's sleeper

5

: children's pajamas usually with feet

—usually used in plural

6

chiefly British : a small earring or stud worn to keep the hole of a pierced ear from closing

7

: mole entry 2 sense 4

Synonyms of sleeper

• slumberer

Examples of sleeper in a Sentence

Sleepers were awakened by the sound of a loud crash.

He may turn out to be the sleeper in this year's election.

The movie was the summer's sleeper.

The movie became the sleeper hit of the summer.

Recent Examples on the Web

Neither are the hundreds of Amazon reviewers that give this lightweight quilt their stamp of approval as hot sleepers. —Stephanie Osmanski, Better Homes & Gardens, 9 May 2026

Kiss night sweats goodbye with these cooling pillows and this dual-sided cooling comforter, which is breathable, promotes airflow, and was designed with hot sleepers in mind. —Ali Faccenda, PEOPLE, 8 May 2026

The HomeSmart Products King Size Weighted Blanket is built specifically for shared use — queen and king sizes are large enough to share with a partner while maintaining consistent weight distribution, so the blanket feels balanced for one or two sleepers. —Samantha Agate, Kansas City Star, 7 May 2026

Queen and king options like the HomeSmart Products King Size Weighted Blanket are large enough to drape across two sleepers while keeping weight balanced. —Samantha Agate, Charlotte Observer, 7 May 2026

Word History

First Known Use

12th century, in the meaning defined at sense 1

Phrases Containing sleeper

• heavy sleeper
• light sleeper
• sleeper cell
• sleeper sofa
• sound sleeper

Rhymes for sleeper

• beeper
• cheaper
• creeper
• deeper
• keeper
• reaper
• steeper
• sweeper
• beekeeper
• bookkeeper
• doorkeeper
• gamekeeper

Kids Definition

sleeper

noun

sleep·​er ˈslē-pər 

1

: one that sleeps

2

: a horizontal beam to support something on or near ground level

3

: sleeping car

4

: someone or something considered unlikely to succeed that suddenly becomes successful