The Rice University Neologisms Database

used to express disgust or dislike of something; another way of saying “yuck” Easier to describe something that is gross, especially for little kids who often create sounds to represent certain words. Many words have been formed through sound symbolism (ie. yuck) and still considered slang. This neologism may has similar properties and could be a phonetic change of "eww," which also shows disgust of something. The change shifts from eww [labiovelar approximant 'w' as in way] to eesh [fricative post alveoloar 's' as in dasher]. I now hear it mostly used with female teens and college kids possibly to sound childish and cute. There have been many different spellings of this word as well such as 'yish.'