split-second

1 of 2

adjective

split-sec·​ond ˈsplit-ˈse-kənd 

1

: occurring in a split second

a split-second decision

2

: extremely precise

split-second timing

split second

2 of 2

noun

: a fractional part of a second : flash

Synonyms of split-second

Adjective

• instantaneous
• immediate
• instant

Noun

• minute
• second
• moment
• heartbeat

Examples of split-second in a Sentence

Adjective

a day trader who is used to making split-second decisions

Noun

In a split second, it was all over.

a devastating accident can cause everything in your life to change in a split second

Recent Examples on the Web

Adjective

Late decision costs Twins A split-second decision by Lewis on an unfamiliar play hastened the end of Saturday’s game. — Dan Hayes, New York Times, 2 Aug. 2026

Trump’s Truth Social is launching a premium ‘Truth API’ that sells Wall Street traders split-second early access to his market-moving posts, stoking new criticisms of insider trading and self-enrichment in the Oval Office. — Bernard Condon, Los Angeles Times, 2 Aug. 2026

Noun

In the days leading up to Saturday’s game against the Saints, Bennett and Simpson split second-team reps during the teams’ joint practice. — Los Angeles Times, 22 Aug. 2026

Rodriguez turning his brain off for a split second in a game that was long, long over is somewhat forgivable. — Mark Harris Outkick, FOXNews.com, 19 Aug. 2026

Word History

First Known Use

Adjective

1944, in the meaning defined at sense 1

Noun

1912, in the meaning defined above

Rhymes for split-second

• beckoned
• reckoned
• second
• seconde
• femtosecond
• microsecond
• millisecond
• nanosecond
• picosecond

Kids Definition

split second

1 of 2 noun

: a small fraction of a second : flash

split-second

2 of 2 adjective

1

: occurring in a split second

a split-second decision

2

: extremely precise

split-second timing