The tool for keyword extraction developed within the AXMEDIS project have been designed for working in a multilingual environment and new algorithms have been developed to generate keywords with higher representativeness for content search and identification. The paper specifies the linguistic criteria followed for building language resources for French, Italian, and German, which are comparable to those available for English and the algorithms used for enhancing keyword performance. The new algorithm extracts keyword collocations from the document and generates multiword keywords. The use of multi-term descriptors is a good means to better identify the content. The precision obtained with respect to mono-term keyword increase the performance of 100% relative factor.