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

However, traditional memory foam also had some drawbacks, including excessive sinkage for some sleepers and a tendency to retain heat during the night. —Jason Phillips, USA Today, 25 Mar. 2026

In many cases, the number of sleep spindles a person can generate (and therefore, whether or not someone is a deep sleeper) is inherited. —Laura Kiniry, Popular Science, 25 Mar. 2026

This option is ideal for side or back sleepers who want extra support, but with a less rigid structure. —Kristine Thomason, Vogue, 25 Mar. 2026

This bed is a solid choice if co-sleepers can’t decide between a soft or firm mattress. —Nashia Baker, Architectural Digest, 19 Mar. 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