taru-adjective, adverb taking the 'to' particle
incessant; constant stream
Obsolete literary term describing an unending flow of people or traffic, often used with として or たる.
往来は絡繹として絶えなかったと、古い紀行文に記されている。
It is recorded in an old travelogue that the traffic was incessant.
The exact derivation is uncertain; the kanji 絡 (entwine) and 繹 (continuous) suggest an unbroken thread, fitting the meaning of an incessant flow.