mala: 'stains', is a name for the 3 kammically unwholesome roots (akusala-mūla); greed, hate and delusion (lobha, dosa, moha).

Buddhist Dictionary, Manual of Buddhist Terms and Doctrines, by NYANATILOKA MAHATHERA

mala [mala] impurity. The three unwholesome roots akuśala-mūla, namely, greed (lobha), hatred (dveṣa) [dosa], and delusion (moha) are mentioned as impurities in the Buddhist literature.

Buddhānusmṛti - A Glossary of Buddhist Terms

Majjhima Nikāya. Vattha. Saṃyutta Nikāya. Mala.

Mala (nt.) [Vedic mala, see etym. under malina. The Dhtm (395) only knows of one root mal or mall in meaning "dhāraṇa" supporting, thus thinking of māḷaka] anything impure, stain (lit. & fig.), dirt. In the Canon mostly fig. of impurities. On mala in similes see J.P.T.S., 1907, 122. -- S i.38 (itthi malaŋ brahmacariyassa), 43 (id.); A i.105 (issā˚); Sn 378, 469, 962, 1132 (=rāgo malaŋ etc. Nd2 500); Nd1 15, 478 sq.; Dh 239 sq.; Vbh 368 (tīṇi malāni), 389 (nava purisa -- malāni); Pv ii.334 (macchera˚); PvA 45 (id.), 80 (id.), 17 (citta˚); Sdhp 220. -- Compar. malatara a greater stain A iv.195=Dh 243. -- See alsomāla.
   -- âbhibhū overcoming one's sordidness S i.18; J iv.64. -- majjana "dirt wiper," a barber Vin iv.308 (kasāvaṭa m. nihīnajacca); J iii.452; iv.365.

Pali-English Dictionary, TW Rhys Davids, William Stede,

mala: n. 垢

巴漢辭典 編者：(斗六) 廖文燦

dri ma

[translation-san] {LCh,C,MSA} mala

[translation-eng] {Hopkins} stain; taint; defilement; contamination

[comments] compare: zag pa (contaminant, contamination) and sgrib pa (obstruction, defiled)

Jeffrey Hopkins' Tibetan-Sanskrit-English Dictionary