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

The reminders come during back-to-school week every year, but the hair-raising video showed how a split-second decision could be the difference between life and death. — Frank Witsil, Freep.com, 11 Sep. 2026

The split-second delay between hitting send and receiving the delivery confirmation is known as the Round-Trip Time (RTT)—and that tiny gap is where the vulnerability lies. — Justyn Newman, PC Magazine, 9 Sep. 2026

Noun

Clutching an aerial hoop on a Johannesburg circus stage, a young performer pauses for a split second before launching into the air and gliding, drawing cheers from the crowd below. — ABC News, 18 Sep. 2026

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

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