Two true facts that can be validly known about any existent phenomenon.
(1) In Hinayana, two types of validly knowable phenomena into which all existent phenomena can be divided: superficially true and deepest true phenomena. (2) In Gelug Mahayana, two true facts that can be validly known about any existent phenomenon. (3) In non-Gelug Mahayana, all existent phenomena cognized with dualistic appearance-making and cognized without dualistic appearance-making.
Tibetan: bden-pa gnyis
J Hopkins: the two truths [i.e. ultimate truth (don dam bden pa, paramArtha-satya); and conventional truth (kun rdzob bden pa, samvRti-satya)].