Majjhimā-patipadā: 'Middle path', is The Noble Eightfold Middle Path which, by avoiding the two extremes of sensual lust and self-torment, leads to enlightenment and deliverance from suffering.
To give oneself up to indulgence in sensual pleasure kāma-sukha the base, common, vulgar, unholy, unprofitable; and also to give oneself up to self-torment atta-kilamatha the painful, unholy, unprofitable, both these two extremes the Perfect One has avoided and has found the Middle path see: magga which causes one both to see and to know, and which leads to peace, to discernment, to enlightenment, to Nibbāna. It is the Noble 8-fold path, the way that leads to the ceasing of suffering, namely: right understanding, right thought, right speech, right bodily action, right livelihood, right effort, right awareness or mindfulness, and right concentration; S. LVI, 11.
Maha Thera Nyanatiloka. Manual of Buddhist Terms and Doctrines, Buddhist Publication Society, first edition 1952.