Development of lexical resources is, along with grammar development, one of the main efforts when building multilingual NLP applications. In this paper, we present a tool-based approach for more efficient manual lexicon development for a spoken language translation system. The approach in particular addresses the common problems of multilingual lexica including the redundancy of encoded information and inconsistency of lexica of different languages. The general benefits of this practical tool-based approach are clear and user-friendly lexicon structure, inheritance of information inside of a language and between different system languages, and transparency and consistency of coverage between system languages. The visual tool-based approach is user-friendly to linguistic informants that dont have previous experience of lexicon development, while at the same time, it still is a powerful tool for expert system developers.