second nature

American  

noun

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.

---

second nature British  

noun

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

---

second nature Idioms  

1. A habit or mode of behavior so long practiced that it seems innate, as in Driving in heavy traffic is second nature to Chris. This expression is a shortened form of an ancient proverb, Custom (or usage) is a second nature, first recorded in 1390. It alludes to the fact that very frequently repeating something makes it seem completely natural or inborn.

---

Etymology

Origin of second nature

First recorded in 1655–65

Example Sentences

Kwan said she would attend presentations with her sales team and rehearse what she saw in the mirror “over and over and over again” until it became second nature.

From MarketWatch • Jun. 23, 2026

It takes an exceptional piece of art to inspire audiences to think twice about what comes as second nature, to choose compassionate contemplation over ardent debate.

From Salon • Apr. 9, 2026

For example, cybersecurity training could teach simple, practiced routines and focus on creating habits, so that avoiding risky links becomes second nature.

From The Wall Street Journal • Dec. 9, 2025

He's still a teenager whose pace and ability to ghost past defenders is second nature to him.

From BBC • Oct. 12, 2025

How strange to have to work so hard on something that used to be second nature.

From "Malala: The Girl Who Stood Up for Education and Changed the World" by Malala Yousafzai