1. Godan verb with 'ku' ending, Intransitive verb

   to be effective; to take effect; to be good (for)

   usu. 効くsee 薬が効く

   この丸薬は心臓に効く。

2. to work; to function well

   usu. 利く for body senses, functions, etc.see 目が利く

3. to be possible (to do, use, etc.); to be able to

   see 割引が効く

4. Godan verb with 'ku' ending, Transitive verb

   to taste (alcohol); to try

   see 聞く

Also written 利く【きく】kiku