dṛḍha-bhāvanayā tyakta-pūrvāpara-vicāraṇam
dṛḍha-bhāvanayā tyakta-pūrvāpara-vicāraṇam |
yad ādānaṁ padārthasya vāsanā sā prakīrtitā ||
(Muktikā Upaniṣad: 2.56)
“[Mental] Clinging to an object out of strong fancy without prior or subsequent deliberation is said to be a vāsanā.”