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

Recent research from my team and me helps explain why this split-second pause happens, offering insight not only into elite athletic performance, but also how people make everyday decisions when the potential outcome isn’t clear. —Eric Yttri, The Conversation, 12 Feb. 2026

These guys have to make a split-second decision, and the men and women on our field are incredible. —Ryan Morik, FOXNews.com, 5 Feb. 2026

Noun

Judges score the flips and spins, including pretzel-like shapes with skis splayed or crossed, before the skiers pull up at the last split second and slam skis-first into the landing area, kicking up a spray of snow. —ABC News, 16 Feb. 2026

However, Los Angeles Dodgers second baseman Miguel Rojas’ throw home beat the sliding Kiner-Falefa by a split second. —Peter Sblendorio, New York Daily News, 10 Feb. 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