• Part-of-speech (word categories) • Morphology – Phrase and Syntax • Rewrite rules, parsing – Sentences and Discourse – Semantics and Pragmatics

• Words are fundamental building block of languages • Classify words into different classes (categories) based on their uses • Two related areas of evidence – Semantic behavior • The word’s contribution to the phrase that contains it – Syntactic or grammatical behavior • The actual syntactic structures in which the word may play a role • Traditionally named part-of-speech (POS) • Four important part-of-speech are nouns, verbs, adjectives, and adverbs 4Word Classes or Categories • The syntactic classes of words (part-of-speech) are traditionally divided into about 8 classes – E.g. noun, verb, adjective, adverbs, prepositions, conjunctions, determiners, pronouns,… – There are well-established sets of abbreviations for naming these classes, referred as POS tags • E,g.: noun (N), verb (V), adjective (A)