Thesauri have been used for literary composition since their inception in 1852, butrnnowadays their primary use is for information retrieval. Even they are among therncrucial components of retrieval systems which are typically used for enhancingrnindexing operations and query expansions during searching.rnEven though Amharic language has been a written language for a couple ofrncenturies and huge volumes of Amharic electronic documents are accumulated,rnnot much has been done towards the development of effective and efficientrnAmharic retrieval systems. In this research work much effort has been exerted torngenerate thesaurus automatically for text retrieval in order to help therndevelopment of an effective and efficient Amharic retrieval system.rnThe development of the automatic thesaurus generation system is based on thernWOROSPACE model. The WOROSPACE model is derived from the inverted filernindex by applying Random Projection algorithm for dimensionality reduction.rnNearest Neighboring clustering algorithm is employed to generate thesaurusrnautomatically from the WOROSPACE model constructedrnAn encouraging result is obtained in the experimentation of the system onrnAmharic Bible documents. During experimentatIOn the accuracy of thernautomatically generated thesaurus is evaluated The result on a random sample ofrnten terms shows that the system has accuracy of 58%. To further investigate itsrnapplicability for Amharic information retrieval, the thesaurus is integrated to an IRrnsystem for query expansion. The retrieval system is tested with and without usingrnthesaurus in order to show the improvement made 111 retrieval effectiveness.rnPerformance analysis shows that the recall of the system while using thesaurus isrnsuperior to not using it. The average recall values are 73.34% and 3729% afterrnand before using thesaurus for query expansion, respectivelyrnkeywords Amharic Thesaurus , WORDS PACE, Information Retrieval (IR)