lisping

1. To pronounce the consonant ‘s’ imperfectly; to give ‘s’ and ‘z’ the sounds of ‘th’ (/θ/). This is a speech impediment common among children.
2. To speak with imperfect articulation; to mispronounce, such as a child learning to talk.
3. To speak hesitatingly and with a low voice, as if afraid.
4. To express by the use of simple, childlike language.
5. To speak with reserve or concealment; to utter timidly or confidentially.

   to lisp treason

noun

That which is spoken in a lisp.