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

Aparicio resists drawing conclusions, privileging an experiential approach with its own rhythms, ambitious in scope yet intimate in focus, that could well become an arthouse sleeper. — Jay Weissberg, Variety, 13 Aug. 2026

For stomach sleepers or devoted pillow fluffers, consider that high praise. — Yelena Moroz Alpert, Architectural Digest, 13 Aug. 2026

The Great Bay Home Queen Jersey Sheets are made with breathable, T-shirt-style fabric that keeps hot and cold sleepers comfortable, no matter the weather. — Sian Babish, PEOPLE, 12 Aug. 2026

The new camper will be available in both two-sleeper and four-sleeper pop-up versions with rear- or all-wheel drive. — New Atlas, 11 Aug. 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