A small child given to running around screaming. Unlike well-socialized children, who only scream when under duress (injury, physical attack by a large snake) a screechling will emit earbleeding screams apparently just to hear the sound of its own voice. These are often found in small packs in shopping malls and supermarkets, usually accompanied by mothers who barely acknowledge the screechlings' existence.
"Gads, did you hear the little screechling in the mall elevator? I think it ruptured my left eardrum. I don't scream that loud during an orgasm for crying out loud."