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

An erratic sleeper whose pattern does not fit neatly into any other category. — Hanna Wickes, Charlotte Observer, 22 July 2026

The blanket strikes the right balance between heavy and light—a quality that even warm sleepers found to be equal parts cooling and comfortable during our testing period. — Alicia Geigel, Southern Living, 22 July 2026

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

Launched in 2017, the all-inclusive Andean Explorer is South America’s first luxury sleeper train and traces one of the world’s highest rail routes through the Andes. — Susmita Baral, Travel + Leisure, 17 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