NPBUDDH: good spritiual friend (and mentor), person of virtuous conduct, able to guide other people > spiritual mentor (other translations of the Sanskrit term include zhīshí 知識, shànyǒu 善友, qīnyǒu 親友, shèngyǒu 勝友, shànqīnyǒu 善親友); SANSKRIT kalyāṇamitra, PALI kalyāṇa-mitta
NPfigurative"teacher" [Note that 善in this construction is a non-restrictive modifier: not of those in the know, a good one...]