kusala-mūla: the 'wholesome roots' or 'roots of wholesome action', are greedlessness (alobha), hatelessness (adosa), and non-delusion (amoha; s. mūla). They are identical with kusala-hetu (s . paccaya, 1).

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

kuśalamūla [kusala-mūla] root of goodness. Kuśalamūla is the root of goodness or the wholesome action. The roots are detachment (alobha), absence of hatred (adoṣa) [adosa], and non-delusion or absence of ignorance (amoha), that is, wisdom. Detachment is the absence of greed. Hatelessness means the absence of hatred. These two dharma-s lead to the formation of generosity and loving-kindness respectively.

     Non-delusion means absence of ignorance, and presence of knowledge of action and its result. It also means knowing and understanding the scriptures and the dharma, knowledge of insight, path and fruition.

Buddhānusmṛti - A Glossary of Buddhist Terms

Aṭṭhasālinī. I. 209, 233-235, 242, 245, 254-255, 379. Avadāna Kalpalatā. VI. 52; XIX. 144. Dīgha Nikāya. Dasuttara, Sampasādanīya, Saṅgīti. Majjhima Nikāya. Sammādiṭṭhi.

kuśala-mūla

(Sanskrit; Pāli, kusala-mūla). Collective name for the three roots of good, being non-greed (arāga), non-hatred (adveṣa), and non-delusion (amoha). Expressed in a positive form they correspond to unselfishness, benevolence, and understanding. All good or virtuous states of consciousness are seen as ultimately grounded in one or more of these three. They are the opposite of the three roots of evil (akuśala-mūla) or unwholesome mental states of greed (rāga), hatred (dveṣa), and delusion (moha).

A Dictionary of Buddhism, Oxford University Press, 2003, 2004 (which is available in electronic version from answer.com)