Dictionary Definition:
Apāyin (adj.) [fr. apāya] going away J i.163 (aḍḍha- rattāvɔapāyin = aḍḍharatte apāyin C.). -- an˚ not going away, i. e. constantly following (chāyā anapāyinī, the shadow) Dh 2; Th 1, 1041; Miln 72.