The term “tongue thrust” refers to an abnormal, tongue-forward swallow. The tongue moves horizontally toward and against the front teeth during the swallow, instead of moving vertically up to the hard palate.
There are other terms used for an anterior, horizontal swallow: a reverse swallow, an infantile swallow (referring to the infant’s tongue that moves horizontally when swallowing), and a juvenile swallow. They all pretty much mean the same thing.
Personally, I describe (and I’m rather partial to) a tongue thrust “horizontal” swallow. It specifically describes the tongue’s plane of movement during the actual swallow.
Sometimes the term tongue thrust is used, minus the word “swallow.” Some professionals use the term comprehensively for any tongue that moves abnormally forward during any function—speaking, chewing, or swallowing.
I’ve seen the term "tongue thrust" applied to interdental speech productions (tongue against teeth) of “t”, “d”, and “n”. Personally, in this case, I choose not use the descriptive term “tongue thrust.” I feel it’s more accurate to say the speech sounds are produced with a horizontal tongue movement that results in interdental speech sounds. I also apply the same principle to a frontal /s/. For a frontal /s/ the tongue moves horizontally but I would not label it a “tongue thrust.”
A "tongue thrust" is typically reserved as a label for an abnormal, anterior swallow.Tongue thrust swallowing therapy is an principle part of myofunctional therapy. It refers to the type of instruction used to generate a good, unharmful, consistent, comfortable, vertical swallow. The term "tongue thrust" is also referred to within the broader category, Orofacial Myology.