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

Symptoms of nocturnal seizures can include signs of sudden awakening with confusion, thrashing, violent movements, screaming, or waking up on the floor.

From BBC • Mar. 10, 2026

It follows 55-year-old Palestinian cab driver Hassan, played with warmth and subtlety by Ehab Salami, as he ferries passengers through the nocturnal streets of Berlin.

From Barron's • Feb. 21, 2026

For much of it the spectacle was the substance: the crudeness, the nocturnal tweeting, the sheer stylistic novelty.

From The Wall Street Journal • Feb. 16, 2026

I would wake earlier, but I think in a past life I was a two-toed sloth or something because I’m nocturnal and I move very slowly.

From Los Angeles Times • Dec. 12, 2025

For Sarai: a doll she coveted from down in Weep, that she’d seen hugged in a sleeping girl’s arms during one of her nocturnal visits.

From "Strange the Dreamer" by Laini Taylor

Related Words

• nightly
• nighttime