Saññā: 1. 'perception', is one of the 5 groups of existence khandha, and one of the 7 mental properties cetasika that are inseparably bound up with all consciousness see: cetanā It is sixfold as perception of the 5 physical sense-objects and of mental objects. It is the awareness of an object's distinctive marks,one perceives blue, yellow, etc.,; S. XXII, 79. If, in repeated perception of an object, these marks are recognized, saññā functions as 'memory' see: Abh. St., p. 68f..
2. saññā stands sometimes for consciousness in its entirety, e.g. in n'eva-saññā-n'āsaññāyatana 'the realm of neither-perception-nor-non-perception'; further, in asaññā-satta 'unconscious beings'. In both cases reference is not to 'perception' alone, but also to all other constituents of consciousness. Cf. D. 9.
3. saññā may also refer to the 'ideas', which are objects of meditation, e.g. in a group of 7 ideas, of impermanence anicca-s etc. A. VII, 46; of 10: impurity asubha-s etc. A. X, 56, and another set of 10 in A. X. 60; or to wrong notions, as in nicca, subha-s the notion of permanence, beauty, etc.
Maha Thera Nyanatiloka. Manual of Buddhist Terms and Doctrines, Buddhist Publication Society, first edition 1952.