The Tipiṭaka in Three Languages

Suññatavāra

Abhidhammapiṭaka · Dhammasaṅgaṇī · Vol. 34 · Section 240

[240] Which, on that occasion, is tranquility of mind (cittapassaddhi)? That which on that occasion is tranquility of the aggregate of consciousness (viññāṇakkhandha) — calming down, the act of calming, the act of calming down, the state of being calmed down — the tranquility factor of awakening (passaddhi-sambojjhaṅga): this, on that occasion, is tranquility of mind.

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.

This passage also appears in 3 other places