All the words of a particular language, group, or field of knowledge. Most individuals have a larger receptive vocabulary (understanding of words) than expressive vocabulary (use of words). The developmental process begins around 12 months, with most early words containing one or two syllables. By 18 months, a child will have acquired approximately 50 words, a majority of which are nouns (Owens 2015). During the preschool years, it is hypothesized that children can determine the connection between a word and its referent after a single exposure to the word (fast mapping). Vocabulary growth continues through the formative school years with an increase in specificity of definition and enhanced ability to discern all meanings of a word. New words are continually added throughout the adult years with definitions of words being more abstract and exclusionary (i.e., what an entity is not) and include personal biases and experiences (Hiebert and Kamil 2005...