What is "koalemos"

In Greek mythology, Koalemos is the god of stupidity, mentioned once by Aristophanes, and being found also in Lives by Plutarch. Coalemus is the Latin spelling of the name. Sometimes it is referred to as a daimon, more of a spirit and minor deity.

Otherwise, the word κοάλεμος was used in the sense of "stupid person" or also “idiots"

An ancient false etymology derives from (koeō) "perceive" and (ēleos) "distraught, crazed". Its etymology is not established, however.