Family name Йонак (Jonak 
, Йонак 
, Jonák ) , all over the world, is quite a rare surname. The last name Йонак is habitual in Czechia, where it is quite a rare surname, Austria, and Slovakia. In absolute terms, it is the most numerous in Czechia, Poland, and Bangladesh. Also, Йонак is the forename as well as the last name.