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

But this exercise offers a glimpse into the amount of studying that goes into actions on a soccer pitch that may look like split-second decisions, and for penalty shootouts that might not even take place. — Thom Harris, New York Times, 11 July 2026

With inflation squeezing their margins and rideshare platforms demanding a large share of their earnings, a driver’s split-second decision to accept a fare is a high-stakes calculation of business survival. — Christopher S. Tang, The Conversation, 8 July 2026

Noun

The moment the ride paused at the top — the very split second of anticipation before the drop — was equally fantastic, and worth a return trip. — Reeti Malhotra, Sacbee.com, 24 July 2026

Rispoli seemed not totally aware of what happened in the split seconds before the start of the San Diego Handicap. — Bill Center, San Diego Union-Tribune, 19 July 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