In Sanskrit philosophical grammar, vācya is the referent — the reality denoted by a vācaka (the denoting word). In Viśiṣṭādvaita hermeneutics, this distinction is central to understanding the first word of the Tirumantram, the praṇava.
The Āchāryas establish that Nārāyaṇa is the vācya of the praṇava. This means that when one utters 'Oṃ' with proper understanding, what is being pointed to — the ultimate referent — is none other than Nārāyaṇa, the Param Puruṣa, who is the inner Self of all beings and the sole independent reality. Piḷḷai Lokācārya's Mumukṣuppadi unfolds this relationship in depth, showing how the letters of the praṇava (a, u, ma) together denote Bhagavān in His various aspects: as the supreme cause, as the sustainer, and as the inner controller.
The concept of vācya also carries a devotional weight: since Nārāyaṇa is the vācya of all language at its deepest level, the entire Vedic corpus is ultimately a sustained meditation on Him. The Viṣṇu Purāṇa and the Āzhvārs' Divya Prabandham alike affirm that all knowledge, all words, and all meaning converge upon Bhagavān as their final resting-place.