Meaning

adjective at risk of or subject to experiencing something usually unpleasant

adjective subject to legal action

adjective (often followed by `to') likely to be affected with

originFrom Old French lier (“to bind”), from Latin ligō, ligāre (“to bind, to tie”). Compare typologically Russian обя́занный (objázannyj), обяза́тельный (objazátelʹnyj) (akin to вяза́ть (vjazátʹ)).

Etymology from Wiktionary, CC BY-SA 3.0