nocturnal

adjective

noc·​tur·​nal näk-ˈtər-nᵊl 

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 

adverb

Synonyms

• night
• nightly
• nighttime

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

Owls, the nocturnal bird, started flying in circles and clawing at the cage right as the sky was turning dark. —Ella Gonzales, Fort Worth Star-Telegram, 12 Apr. 2024

During solar eclipses, when the sky briefly turns dark, dogs may cower, birds stop flying and grow quiet, and nocturnal creatures emerge. —Mallory Moench, TIME, 7 Apr. 2024

What is not clear is what happens to nocturnal animals when the eclipse occurs, Speck said. —Julia Jacobo, ABC News, 3 Apr. 2024

The study found that mice that ran during the early part of their active phase — the equivalent of the morning for humans, since mice are nocturnal — started off with a lower endurance level than the group running in what would be our afternoon. —Will Stone, NPR, 29 Mar. 2024

But there’s the inconvenient hypocrisy of his own nocturnal havoc to deal with, which is where Fessenden’s update — more talky than bloody, and still plenty bloody — carves out its own moral seriousness about the monsters inside all of us. —Robert Abele, Los Angeles Times, 13 Apr. 2024

The researchers are still unsure of why the nocturnal creatures have such acute eyesight. —Paul Smaglik, Discover Magazine, 11 Apr. 2024

This was a nocturnal ritual for the 22-year-old, dressed in a ball cap and a wool overshirt, whose perch — just over 300 yards up a rocky incline from the United States-Mexico border wall — had become a round-the-clock boarding space for people who had crossed unlawfully onto American soil. —Emily Baumgaertner, New York Times, 11 Apr. 2024

Total eclipses can lead to a period of darkness lasting for several minutes, during which time nocturnal animals stir while confused birds and insects may fall silent, NASA says. —USA TODAY, 8 Apr. 2024

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

Kids Definition

nocturnal

adjective

noc·​tur·​nal näk-ˈtərn-ᵊl 

1

: of, relating to, or occurring in the night

a nocturnal journey

2

: active at night

nocturnal insects

nocturnally

-ᵊl-ē 

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 

1

: of, relating to, or occurring at night

nocturnal myoclonus

2

: characterized by nocturnal activity

a nocturnal form of filariasis