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

Also, the various injuries to Orioles hitters have Coby Mayo as a potential post-hype sleeper and Blaze Alexander as a middle infield option. —Jake Ciely, New York Times, 26 Feb. 2026

Byredo Desert Dawn Eau de Parfum This sultry scent is my favorite of Byredo’s sleeper-hits. —Sophie Wirt, InStyle, 26 Feb. 2026

Another medium-firm option that will deliver crucial neck support is Casper’s original pillow, which is great for all types of sleepers like our contributor Madeleine Luckel, who snoozes on both of her sides, her back, and stomach. —Audrey Lee, Architectural Digest, 26 Feb. 2026

Side sleepers with chronic neck pain swear by the Osteo Cervical Pillow, which by no coincidence, is an Amazon best-seller. —Stephanie Osmanski, Better Homes & Gardens, 25 Feb. 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