A physical characteristic (though, I consider it a birth defect) in which the lingual frenulum (the tissue that keeps your tongue to the bottom of your mouth) extends all the way from the back of the throat to the tip of the tongue. It used to be common practice to cut this tissue, but they aparrently don't do that anymore. For me, I haven't had any kind of problems with speaking or a speech impediment, though don't even begin to ask about french kissing.