Automatic document topic identification; Clustering; Ontology; Social knowledge network; Wikipedia Glossary ADTI Stands for automatic document topic identification Ontology "A model for describing the world, that consists of a set of types (concepts), properties, and relationship types" (Garshol 2004) SKN Stands for social knowledge network WHO Stands for Wikipedia Hierarchical Ontology TF-IDF A term weighting methodology that is commonly used in text mining and in information retrieval. It stands for term frequency-inverse document frequency hi5 An online social networking website RDF Stands for Resource Description Framework. It is a method of representing information to facilitate the data interchange on the Web ASR Stands for automatic speech recognition NMI Stands for normalized mutual information. It is a well-known document clustering performance measure NMF Stands for nonnegative matrix factorization. Nonnegative matrix factorization is a family of algorithms that tries to factor a matrix X into two matrices Y and Z, with the property that all three matrices have no negative elements Clustering Is the process of assigning each input pattern to a group (cluster), such that each group contains similar patterns Taxonomy Is the division of concepts or topics into ordered groups or categories Mohamed S. Kamel: Deceased