The study of sign language semantics aims to describe how meaning is communicated through sign languages. Clearly, many individual signs carry their own meaning; the study of what individual words and signs mean and how the mind classifies them is called lexical semantics. One major categorization of words is into “open-class” (content) words and “closed-class” (function) words. Open-class words include most nouns (e.g., HOUSE, SHOES), verbs (DANCE, READ), and adjectives (red, friendly), which can, and are, constantly being created anew in a language (e.g., EMAIL) and comprise most of the content of an utterance. Because the meanings of open-class words are tied closely to the cognitive science of concepts, the study of the classification and acquisition of content words is frequently the focus of studies ...