puffing

Verb

form-of participle present US

Japanese Meaning

puff の現在分詞形 / （特に寒冷時において）車のエンジンを無人でアイドリングさせ、車内を暖めるために作動させ続ける行為

The old man walked up the hill puffing on his pipe.

老人は丘を登りながらパイプをふかしていた。

Sense（1）

present participle of puff

Sense（2）

(US) Leaving a car engine running unattended, especially in cold weather to warm it up.

It's called "puffing," when drivers start their car and then leave it unattended while running.