The word "nice" once meaning "foolish" and the word "awful" used to mean "full of awe" are examples of semantic shift, which is a change in the meaning of a word over time. Semantic shift can occur for a variety of reasons, such as changes in cultural norms or values, changes in language usage, or shifts in the connotations of a word. In this case, the students and teacher in Robin's linguistics class are most likely discussing semantics, which is the study of meaning in language. Semantics is concerned with how words are used to convey meaning and how meaning is constructed and understood in context. Other areas of linguistics that might be related to semantics include lexical semantics, which is the study of the meaning of individual words, and discourse semantics, which is the study of how meaning is constructed in larger units of language, such as sentences, paragraphs, or texts.