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

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

Seventy-five percent of the species observed exhibited some behavioral response to the eclipse, and most exhibited their evening or nocturnal behaviors. —Geraldine Castro, WIRED, 6 Apr. 2024

At the same time, animals will also come alive in a unique way, particularly nocturnal creatures. —Vanessa Romo, NPR, 6 Apr. 2024

The nocturnal owls don’t hoot but make strange screams and hissings sounds at night. —Karl Schneider, The Indianapolis Star, 1 Apr. 2024

The nocturnal birds have tufts on their heads that look like horns or ears. —Helena Wegner, Sacramento Bee, 28 Mar. 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