second nature

WordReference Random House Learner's Dictionary of American English © 2025

ˈsec•ond ˈna•ture, n. [uncountable]

1. a way of thinking or acting so deeply fixed as to appear automatic:
   After a while, using a mouse on the computer became second nature to him.

WordReference Random House Unabridged Dictionary of American English © 2025

sec′ond na′ture, 

1. an acquired habit or tendency in one's character that is so deeply ingrained as to appear automatic:
   Neatness is second nature to him.

• 1655–65

Collins Concise English Dictionary © HarperCollins Publishers::

second nature noun

1. a habit, characteristic, etc, not innate but so long practised or acquired as to seem so

WordReference Random House Learner's Dictionary of American English © 2025

na•ture /ˈneɪtʃɚ/   n. 

1. [uncountable] the natural world as it exists without human beings or civilization;
   the elements of the natural world, as mountains, trees, animals, or rivers.
2. [uncountable] the laws and principles that guide the universe or an individual.
3. the native character that is part of someone or something:
   [countable] It is a cat's nature to keep itself clean.
4. character, kind, type, or sort: [countable; usually singular]
   What is the nature of your business here?
   [uncountable* often: in + ~]
   The problems are economic in nature.
5. disposition;
   temperament:
   [countable] an evil nature; a kind, loving nature.
6. the simple or primitive condition of humankind before modern civilization:
   [uncountable] to return to nature to live.

Idioms

7. Idioms by nature, as a result of inborn or inherent qualities;
   innately.
8. call of nature, [countable] the need to urinate or defecate.
9. second nature, [uncountable] a habit or way of acting or thinking that has become part of the character of a person:
   He has been a police officer for so long that dealing with emergencies has become second nature to him.

See -nat-.

WordReference Random House Unabridged Dictionary of American English © 2025

na•ture  (nā′chər), n. 

1. the material world, esp. as surrounding humankind and existing independently of human activities.
2. the natural world as it exists without human beings or civilization.
3. the elements of the natural world, as mountains, trees, animals, or rivers.
4. natural scenery.
5. the universe, with all its phenomena.
6. Philosophy the sum total of the forces at work throughout the universe.
7. reality, as distinguished from any effect of art:
   a portrait true to nature.
8. the particular combination of qualities belonging to a person, animal, thing, or class by birth, origin, or constitution;
   native or inherent character:
   human nature.
9. the instincts or inherent tendencies directing conduct:
   a man of good nature.
10. character, kind, or sort:
    two books of the same nature.
11. characteristic disposition;
    temperament:
    a self-willed nature; an evil nature.
12. the original, natural, uncivilized condition of humankind.
13. Biology the biological functions or the urges to satisfy their requirements.
14. a primitive, wild condition;
    an uncultivated state.
15. a simple, uncluttered mode of life without the conveniences or distractions of civilization:
    a return to nature.
16. Philosophy (cap., italics) a prose work (1836), by Ralph Waldo Emerson, expounding transcendentalism.
17. Religion [Theol.] the moral state as unaffected by grace.
18. Idioms by nature, as a result of inborn or inherent qualities;
    innately:
    She is by nature a kindhearted person.
19. in a state of nature:
    • Idioms in an uncivilized or uncultured condition.
    • Idioms without clothes;
      nude;
      naked.
20. Idioms of or in the nature of, having the character or qualities of:
    in the nature of an apology.

• Latin nātūra conditions of birth, quality, character, natural order, world, equivalent. to nāt(us) (past participle of nāscī to be born) + -ūra -ure
• Old French
• Middle English natur(e) 1200–50

na′ture•like′, adj.