The bondage (coalescence) of the Karma-pudgalas (material clusters qua Karma) with the Jīva (soul), due to its auspicious and inauspicious Pariṇāma (1) (to undergo transformation from one state to another one).
bajjhadi kammaṃ jeṇa du cedaṇabhāveṇa bhāvabaṃdho so.
kammādapadesāṇaṃ aṇṇoṇṇapavesaṇaṃ idaro..
(BrDraSam 32)
See - Bhāvabandha.