[210] What, on that occasion, is the faculty of concentration (samādhindriya)?
That which on that occasion is stability of the mind (citta), steadiness, steadfastness, non-wavering, non-distraction, the state of unwavering mentality, calm (samatha), the faculty of concentration, the power of concentration, right concentration, the concentration factor of awakening (samādhi-sambojjhaṅga), a path factor, included in the path — this, on that occasion, is the faculty of concentration.
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.