1) Castilian speaker 2) Childish speaker 3) Imperfect articulator 4) One who avoids sissies 5) One who talkths like thith 6) Speaker 7) Sylvester is one, famously 8) Sylvester or Daffy 9) Talker 10) Talker of a kind 11) Utterer 12) Verbaliser 13) Verbalizer Found on https://www.crosswordclues.com/clue/lisper