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

• dozer
• 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

Its body-contouring design also relieves pressure on side sleeper’s hips and shoulders while supporting the mid section, alleviating joint and back pain, according to the brand. —Maggie Horton, People.com, 22 June 2025

Firm without being too firm Comfortable for most sleepers. —Scott Gilbertson, Wired News, 16 June 2025

Sweaty sleepers, rejoice: Amazon just dropped a hot deal on a lightweight quilt set that will help keep you cool all summer long. —Mariana Best, Better Homes & Gardens, 15 June 2025

Today’s options can accommodate side sleepers, neck pain, pregnancy and every preference for softness. 2. —The Washington Post, San Diego Union-Tribune, 14 June 2025

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