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

Linen fibers, which are derived from the flax plant, are naturally hypoallergenic, absorbent, and antibacterial, so all of us also looked for sheets without synthetic fibers to suit sleepers with sensitive skin. —Nashia Baker, Architectural Digest, 6 June 2026

Neither are the hundreds of Amazon reviewers that give this lightweight quilt their stamp of approval as hot sleepers. —Stephanie Osmanski, Better Homes & Gardens, 6 June 2026

Like the original two-berth Kamelback, the four-sleeper is built atop a Land Cruiser 79 Series pickup, only this time with the double cab needed to seat all four campers. —New Atlas, 2 June 2026

Rhodes went for an avalanche Cody Cutter, and Gunther caught him in a sleeper. —Alfred Konuwa, Forbes.com, 31 May 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