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 of nocturnal

• night
• midnight

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

The nocturnal moth is a central focus in her Spring/Summer 2026 offering, the designer finding herself fascinated by the way a creature that spends its existence in darkness is still so constantly drawn to light. —Rachel Elspeth Gross, Forbes.com, 6 June 2026

While cockroaches are nocturnal and are most active at night, keeping lights on is not a deterrent. —Arricca Elin Sansone, Southern Living, 4 June 2026

Tasmanian devils — agile, mostly nocturnal animals that can roam for 10 miles in a single night — have been extinct on the Australian mainland for more than 3,000 years. —CBS News, 4 June 2026

Modern cities, with their excessive nocturnal lighting, have eaten away at the darkness. —Wyatt Williams, Harpers Magazine, 2 June 2026

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

Rhymes for nocturnal

• diurnal
• eternal
• external
• fraternal
• infernal
• internal
• maternal
• paternal
• pimpernel
• colonel
• journal
• kernel

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