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

The Kansas City Chiefs show, which hit ESPN, ESPN+ and Disney+ on Thursday, Aug. 14, included the adorable, split-second detail in the second episode. —Sabrina Weiss, People.com, 15 Aug. 2025

In addition to his famous perpetual calendar, Klaus also developed split-second, world time, depth gauge, and other sophisticated mechanisms culminating in the Il Destriero Scafusia in 1993, then the world’s most complicated wristwatch. —Oren Hartov, Robb Report, 15 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