taru-adjective, adverb taking the 'to' particle
billowing; rising in clouds
Literary or poetic word describing clouds, dust, or smoke rising thickly. Often used with と (べきべきと). Rare in everyday speech.
Dust billows up thickly.
Clouds billow up beyond the mountains.
The origin is uncertain. It is a reduplicated mimetic word, possibly related to the kanji 冪 (cover, veil), suggesting a spreading or covering motion.