Bound or obliged in law or equity; responsible; answerable.
1748. David Hume. Enquiries concerning the human understanding and concerning the principles of moral. London: Oxford University Press, 1973. § 34.
Subject; susceptible.
A man liable to heart disease.
Exposed to a certain contingency or causality, more or less probable.
(as predicate, with "to" and an infinitive) likely.
Someone is liable to slip on your icy sidewalk.