The phrase oral aversion describes the avoidance or fear of eating, drinking, or accepting sensation in or around the mouth (ex. tooth brushing or face-washing). A typically developing child learns that eating and drinking are fun and positive experiences. A child with an oral aversion has somehow learned that eating and/or drinking is uncomfortable, unpleasant or causes anxiety.
Source: http://www.thefeedingfamily.com/5/post/2011/3/what-is-oral-aversion.html