1 (often foll. by of) a not capable. b lacking the required quality or characteristic (favourable or adverse) (incapable of hurting anyone).
2 not capable of rational conduct or of managing one's own affairs (drunk and incapable).
Derivatives:
incapability n. incapably adv.
Etymology: F incapable or LL incapabilis (as IN-(1), capabilis CAPABLE)
Useful english dictionary. 2012.