nocturnal

adjective

noc·​tur·​nal näk-ˈtər-nᵊl How to pronounce nocturnal (audio)
Synonyms of nocturnal
1
: of, relating to, or occurring in the night
a nocturnal journey
nocturnal activities
2
: active at night
a nocturnal predator
nocturnal insects, such as mosquitoes
nocturnally
näk-ˈtər-nᵊl-ē How to pronounce nocturnal (audio)
adverb

Synonyms of nocturnal

Relevance
See All Synonyms & Antonyms in Thesaurus

Examples of nocturnal in a Sentence

he bought a new telescope so he could pursue his favorite nocturnal hobby of astronomy
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Sometimes called honey bears, kinkajous are nocturnal and live in trees. — Amy McDaniel, Fort Worth Star-Telegram, 21 Aug. 2026 Rabid nocturnal animals can display uncharacteristic daytime exposure. — Perri Ormont Blumberg, FOXNews.com, 17 Aug. 2026 This can trigger strange responses from wildlife, with animals that are typically nocturnal coming out to see what's going on, confused about why night arrived at what feels like the wrong time. — Chelsea Gohd, Space.com, 13 Aug. 2026 Instead, opt for a dimmer yellow light, or—even better—a red light that nocturnal insects can’t see. — Olivia Young, Travel + Leisure, 13 Aug. 2026 See All Example Sentences for nocturnal

Word History

Etymology

Middle English, borrowed from Anglo-French & Late Latin; Anglo-French nocturnel, borrowed from Late Latin nocturnālis "for night use," from Latin nocturnus "of or occurring at night" (from noct-, nox night entry 1 + -urnus, temporal suffix, as in diurnus "of the day") + -ālis -al entry 1 — more at journal

First Known Use

15th century, in the meaning defined at sense 1

Time Traveler
The first known use of nocturnal was in the 15th century

Rhymes for nocturnal

See All Rhymes for nocturnal

Browse Nearby Words

nocturn
nocturnal
nocturnality
See all Nearby Words

Cite this Entry

“Nocturnal.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/nocturnal. Accessed 23 Aug. 2026.

Copy Citation

Kids Definition

nocturnal

adjective
noc·​tur·​nal näk-ˈtərn-ᵊl How to pronounce nocturnal (audio)
1
: of, relating to, or occurring in the night
a nocturnal journey
2
: active at night
nocturnal insects
nocturnally
-ᵊl-ē How to pronounce nocturnal (audio)
adverb
Etymology

from early French nocturnal, nocturnel or Latin nocturnalis, both meaning "nocturnal," derived from earlier Latin noct-, nox "night" — related to equinox

Medical Definition

nocturnal

adjective
noc·​tur·​nal näk-ˈtərn-ᵊl How to pronounce nocturnal (audio)
1
: of, relating to, or occurring at night
nocturnal myoclonus
2
: characterized by nocturnal activity
a nocturnal form of filariasis

More from Merriam-Webster on nocturnal

Nglish: Translation of nocturnal for Spanish Speakers

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

More from Merriam-Webster

Word of the Day

Listen to the pronunciation of prowess

See Definitions and Examples »

Popular in Grammar & Usage

See More

A Who’s Who Regarding ‘Who’s’ and ‘Whose’

How to Pronounce the Trickiest Menu Items

'A' or 'an'? What about before 'h'? An Indefinite Article Guide

Do you 'say your piece' or 'say your peace'?

Why is '-ed' sometimes pronounced at the end of a word?
See More

Popular in Wordplay

See More

Words from the 'Odyssey'

The Longest Long Words List

Even More Words That Sound Like Insults But Aren't

The Words of the Week - Aug. 21

12 Lovely and Unusual Words for the Natural World
See More

Popular

See More

A Who’s Who Regarding ‘Who’s’ and ‘Whose’

Words from the 'Odyssey'

The Longest Long Words List
See More

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
The Missing Letter A daily crossword with a twist
alt-684346df967d5
Add A Letter Quiz Pick the letter that goes in the same spot in fou...
See All