Automatic determination of parts of speech of English words

The classifying of words according to syntactic usage is basic to language handling; this paper describes an algorithm for automatically classifying words according to thirteen commonly used parts of speech: noun, adjective, verb, past verb, adverb, preposition, conjunction, pronoun, interjection, present participle, past participle, auxiliary verb, and plural or collective noun. The algorithm was derived by a computerized study of the words in The Shorter Oxford English Dictionary. In its operation it utilizes a prepared dictionary of around nine hundred words to assign parts of speech to special or exceptional words. Other words are split into affix and kernel parts and assigned a part of speech on the basis of the part-of-speech implications of the affixes and the length of the remaining kernel. An accuracy of 95 per cent is achieved from the point of view of inclusive part of speech, where inclusive part of speech is defined as that string which contains all the parts of speech attributed to the word by the dictionary but which may also contain one or two more parts of speech. Introduction