Automatic classification has become an important research area due to the rapid increase of digital information today. Evidently, manual classification of documents is a tough work due to occurrences of vocabulary ambiguities of classification schemes as well as the language used in the text in hand.

In our study, we made an attempt to resolve this matter. This research has developed a computer programme that can automatically classify a given text document based on a well developed ontology. Therefore, the user gets correct options of classification just after feeding the document to the new system. The new ontology is a domain ontology which is based on the Dewey Decimal Classification scheme and the Sears list. Data was obtained for classification accuracy for both manual and automatic methods. Moreover, the relationship between the vagueness of language in documents and the inaccuracy of classification were