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

Cody Rhodes shook off the sleeper and hit a suicide dive on Zayn. — Alfred Konuwa, Forbes.com, 18 July 2026

The Foamy Sleeping Pad comes in a variety of sizes to accommodate nearly every sleeper. — Clay Abney, Travel + Leisure, 16 July 2026

The result is a superlative and affordable four-sleeper camper van that offers features usually reserved for much more expensive custom camper van builds. — New Atlas, 15 July 2026

The answer can help determine the best support level for hip, shoulder, and spinal alignment—firm for stomach sleepers, soft for side sleepers, and medium firmness for back sleepers. — Yelena Moroz Alpert, Architectural Digest, 14 July 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