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

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

Here, at one of Portugal’s revered proving grounds, that split-second commitment unleashes a wave of momentum that feels endless. —Viju Mathew, Robb Report, 30 Aug. 2025

Kristin Henning, director of the Juvenile Justice Clinic at Georgetown University's law school, said that matters when law enforcement is making a split-second decision. —Jade Jackson, IndyStar, 30 Aug. 2025

Noun

They’ll be decided in the split second after the click — where expensive, high-intent traffic is either captured or lost. —Sindhya Valloppillil, Forbes.com, 19 Aug. 2025

The Padres challenged the call, which was overturned after replay showed Hamilton’s hand came off the bag for a split second. —Kevin Acee, San Diego Union-Tribune, 10 Aug. 2025

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