indriya: 'faculties', is a name for 22, partly physical, partly Mental, Phenomena often treated in the Suttas as well as in the Abhidhamma. They are:
6 bases (āyatana):
1. eye: cakkhu
2. ear: sota
3. nose: ghāna
4. tongue: jivhā
5. Body: Kāya
6. Mind: mano
7. femininity: itthi
8. Masculinity: purisa
9. vitality: jīvita
5 Feelings (vedanā)
10. bodily pleasant Feeling: Sukha
11. bodily pain: Dukkha
12. gladness: somanassa
13. sadness: domanassa
14. indifference: upekkhā
5 Spiritual Faculties (s. Bala)
15. Faith: saddhā
16. energy: Viriya
17. Mindfulness: ([[[Sati]])]
18. Concentration: Samādhi
19. ([[[Wisdom]])]: paññā
3 Supermundane Faculties
20. the assurance: 'I shall know what I did not yet know!': aññātañ-ñassāmīt' indriya
21. the faculty of highest Knowledge: aññindriya
22. the faculty of him who knows: aññātāvindriya.
(1-5, 7-8) are physical; (9) is either physical or Mental. All the rest are Mental.
(14) (s. upekkhā) is here merely indifferent Feeling (= adukkha-m-asukhā vedanā, i.e. 'neither pleasant nor unpleasant Feeling') and not identical with that highly ethical state of Equanimity (= tatramajjhattatā, i.e. 'keeping everywhere the middle', the equipoise of Mind), also called upekkhā which belongs to the Group of Mental Formations (Sankhāra-Kkhandha; s. Tab II).
(20) arises at the moment of entering the Sotāpatti-Path (sotāpatti-Magga), (21) on reaching the Sotāpatti-Fruition (sotāpatti-phala), (22) at attaining the Arahat-Fruition (arahatta-phala). For the three last, s. Ariya-puggala.
The faculties, excepting (7) and (8), Form one of the 24 conditions (Paccaya 16).
In Vibh. V all these faculties are treated in the above order, whereas S.XLVIII enumerates and explains them by way of the above indicated groups, leaving only 20-22 unexplained. See Vis XVI; Path 138ff.
For the 5 spiritual faculties (15-19), s. The Way of Wisdom (Wheel 65/66).