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 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

Made from 270-thread-count long-staple cotton, the sheets have a crisp, breathable feel that's especially attractive to hot sleepers who prefer something lighter than silky sateen. — Jacorey Moon, Architectural Digest, 7 Nov. 2026

Both models include an interior kitchen block behind the driver's seat and a four-sleeper pop-up layout. — New Atlas, 6 Nov. 2026

Good sleepers also had significantly larger total brain volume, including more gray and white matter, than their counterparts who did not sleep well. — Emily Kay Votruba, EverydayHealth.com, 4 Nov. 2026

This is vital, as sleepers might otherwise act out their dreams and harm themselves or others. — Rj MacKenzie, Popular Science, 29 Oct. 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