Tāṭastha Lakṣaṇa — The Contingent Defining Feature
Tāṭastha Lakṣaṇa (Sanskrit: tāṭa = riverbank + stha = standing; 'one standing on the bank — neither in water nor on land'; metaphorically 'on the boundary, contingent') refers to a characteristic used to define an entity by its relation to something external, not by the entity's own inner nature.
The Riverbank Analogy: Just as someone standing on a riverbank is neither fully in the river nor on dry land, tāṭastha lakṣaṇa describes an entity through a contingent, intermediate characteristic. The classic example: the tāṭastha lakṣaṇa of Brahman is 'jagat-kāraṇa' (cause of the universe) — this is a relational, contingent description. If creation were absent, Brahman would still exist; this characteristic would not apply.
Paired with Svarūpa Lakṣaṇa: Every entity has both svarūpa lakṣaṇa (intrinsic essential character) and tāṭastha lakṣaṇa (contingent relational character). For the ātman: its svarūpa lakṣaṇa is consciousness (jñāna); its tāṭastha lakṣaṇa is 'the experiencer of results of karma' — contingent on being in saṃsāra.
Practical Significance: Distinguishing these two types of characteristics guards against a category error. Karma and bondage are tāṭastha to the ātman — they can and will be removed by Bhagavān's grace. The ātman's śeṣatva (essential servant-nature to Bhagavān) is svarūpa — permanent and inseparable.