Asubha: Impurity, loathsomeness, foulness, disgust. - In Vis.M VI, it is the cemetery contemplations sīvathika that are called meditation-subjects on impurity asubha-kammatthāna; see. bhāvanā. In the Girimananda Sutta A. X., 50, however, the perception of impurity asubha-saññā refers to the contemplation of the 32 parts of the body see: kāya-gatā-sati. The contemplation of the body's impurity is an effective antidote against the hindrance of sense-desire see: nīvarana and the mental distortion vipallāsa, which sees what is truly impure as pure and beautiful. See XLVI, 51; A. V. 36, Dhp. 7, 8; Sn. 193ff. - The Five Mental Hindrances WHEEL 26, pp. 5ff.
It is the single-most important tool to counteract sensual and sexual greed.
Maha Thera Nyanatiloka. Manual of Buddhist Terms and Doctrines, Buddhist Publication Society, first edition 1952.