Adjective lief has 1 sense
- glad, lief - (`lief' is archaic) very willing; "was lief to go"; "glad to help"
Antonym: unwilling (indirect, via willing)
,
Adverbial lief has 1 sense
- gladly, lief, fain - in a willing manner; "this was gladly agreed to"; "I would fain do it"
,