RhymeZone: sicker definitions

Definitions of sicker:

adjective: (obsolete outside dialects) Certain.
adjective: (obsolete outside dialects) Secure, safe.
adverb: (obsolete outside dialects) Certainly.
adverb: (obsolete outside dialects) Securely.
verb: (intransitive, literally, figuratively) To percolate, trickle, or seep; to ooze, as water through a crack.

(Definitions from Wiktionary)