1.
diurnal habit; being active during the day
The biological habit of being active during daytime and resting at night — applied to animals as a classification of their activity pattern. Directly contrasted with 夜行性 ('nocturnal habit'). Used mainly in biology, zoology, and nature writing.
犬は昼行性だ。
Dogs are diurnal.
多くの鳥は昼行性の動物だ。
Many birds are diurnal animals.
人間はもともと昼行性なので、夜勤を続けると体調を崩しやすい。
Humans are naturally diurnal, so continuously working night shifts tends to harm one's health.
Compound of 昼 ('daytime'), 行 ('moving; acting'), and the suffix 性 ('nature; property'). Used in biology and natural history to classify animals by their daily activity pattern. Almost always contrasted with 夜行性 ('nocturnal') and occasionally with 薄明性 ('crepuscular').
USAGE:
- Most common in nature documentaries, biology textbooks, zoo exhibits, and pet-care articles.
- Typically appears as a predicate noun (犬は昼行性だ) or as a modifier (昼行性の動物).
- When discussing humans, the word often comes up in health articles warning that night-shift work disrupts our natural daytime rhythm.
- Also written 昼光性 (with 光, 'light') in some biological sources, though 昼行性 is the standard form.
COMMON COLLOCATIONS:
- 昼行性の動物: a diurnal animal
- 昼行性である: to be diurnal
- 完全な昼行性: strictly diurnal
- 昼行性の生活: a daytime lifestyle
- 人間は昼行性だ: humans are diurnal
SIMILAR WORDS:
- 夜行性: nocturnal — the direct antonym; used for animals active at night such as owls, bats, and raccoons.
- 薄明性: crepuscular — active at dawn and dusk; a narrower category between 昼行性 and 夜行性.
- 生活リズム: daily rhythm; lifestyle rhythm — everyday word for people's daily routine; used when talking about humans rather than animal biology.
- 日中活動: daytime activity — descriptive phrase; 昼行性 sums the same idea up as a single biological label.
- 概日リズム: circadian rhythm — the broader biological 24-hour cycle underlying diurnal and nocturnal behavior.