nocturnal

American  

[nok-tur-nl] / nɒkˈtɜr nl /

adjective

1. of or relating to the night (opposed to diurnal).

2. done, occurring, or coming at night.

   nocturnal visit.

   Synonyms:

   nighttime

3. active at night (opposed to diurnal).

   nocturnal animals.

4. opening by night and closing by day, as certain flowers (opposed to diurnal).

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noun

1. Archaic. an astrolabe for telling time at night or for determining latitude by the position of certain stars in reference to Polaris.

nocturnal British  

/ nɒkˈtɜːnəl /

adjective

1. of, used during, occurring in, or relating to the night

2. (of animals) active at night

3. (of plants) having flowers that open at night and close by day

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nocturnal Scientific  

/ nŏk-tûr′nəl /

1. Occurring at night.

2. Most active at night. Many animals, such as owls and bats, are nocturnal.

3. Having flowers that open during the night and close at daylight. Nocturnal plants are often pollinated by moths.

4. Compare diurnal

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Other Word Forms

• nocturnality
  noun
• nocturnally
  adverb
• nonnocturnal
  adjective
• nonnocturnally
  adverb
• seminocturnal
  adjective
• unnocturnal
  adjective
• unnocturnally
  adverb

Etymology

Origin of nocturnal

From the Late Latin word nocturnālis, dating back to 1475–85. See nocturn, -al ¹

Explanation

If something is nocturnal, it belongs to or is active at night. That includes vampires, owls that like to hunt by moonlight, and that roommate who stays up playing video games until the wee hours of the morning. The adjective nocturnal comes from the Late Latin nocturnalis, which means “belonging to the night." You've probably heard of nocturnal animals, like bats and fireflies, who sleep during the day and come out to play when the sun goes down. The opposite of nocturnal is diurnal, meaning active during the daytime — but you probably won't be using that word much unless you're a zoologist.

Example Sentences

Nocturnal animals obviously depend on having adequate darkness for the kind of eyesight they've evolved and the nighttime behavior they've evolved to carry out in the dark of night.

From Salon • Apr. 15, 2025

He also starred in thriller Nocturnal Animals, which he won a Golden Globe for in 2017, Anna Karenina, Godzilla and Tenet.

From BBC • Mar. 19, 2024

Nocturnal flying insects: Examples of nocturnal flying insects are moths, beetles and mosquitoes.

From Science Daily • Oct. 27, 2023

Next, take a 15-minute sweaty aerobic session through the Nocturnal Wasteland looking more and more like an extended scene from “Mad Max: Fury Road.”

From Washington Times • Sep. 19, 2023

Nocturnal defense had ceased to be a concern after many successive nights of tranquil woodland repose.

From "A Walk in the Woods" by Bill Bryson

Related Words

• nightly
• nighttime