'impurities', corruptions, imperfections (a frequent rendering by 'defilements' is better reserved for kilesa).
A list of 16 moral 'impurities of the mind' (cittassa upakkilesa) is mentioned and explained in M.7 & 8 (WHEEL. 61/62):
- 1. covetousness and unrighteous greed (abhijjhā-visamalobha),
- 2. ill will (vyāpāda ),
- 3. anger (kodha ),
- 4. hostility (upanāha ),
- 5. denigration (makkha ),
- 6. domineering (palāsa ),
- 7. envy (issā ),
- 8. stinginess (macchariya ),
- 9. hypocrisy (māyā ),
- 10. fraud (sātheyya ),
- 11. obstinacy (thambha ),
- 12. presumption (sārambha ),
- 13. conceit (māna ),
- 14. arrogance (atimāna ),
- 15. vanity (mada ),
- 16. negligence (pamāda ).
There are 3 groups of upakkilesa pertaining to meditation :
(a) 9 mental imperfections occurring in 'one devoted to higher mental training' (adhicitta);
3 coarse ones - evil conduct in deeds, words and thoughts;
3 medium - thoughts of sensual desire, ill will and cruelty;
3 subtle - thoughts about one's relatives, one's country and one's reputation (A.III.100).
(b) 18 imperfections in the practice of mindfulness of breathing (ānāpāna-sati), mentioned in Pts.M., ānāpāna-kathā (tr. in Mindfulness of Breathing, by Ñānamoli Thera (p. 60; BPS).
(c) 10 'imperfections of insight' (-meditation, vipassanūpakkilesa); s. visuddhi V.