This paper describes the structure and compilation process of a Hong Kong Chinese Lexicon being developed for a forthcoming Cantonese keyboard. The lexicon contains more than 120,000 headwords, including common words and high-frequency named entities, and incorporates information such as Jyutping romanization, indicative word frequency, simple translations in five languages (English, Hindi, Indonesian, Nepali, Urdu), disambiguation, POS information, speech register and cross-register synonyms. The lexicon improves the Chinese learning experience of CAL students in two ways: (a) introducing and promoting the effective usage of input methods and dictionaries for learners that facilitate them to locate the correct choice of word or phrase within a particular context, and (b) providing additional register-specific data that enable advanced learners to further expand their vocabulary. This lexicon can be used in conjunction with WordNet or LIWC (Linguistic Inquiry and Word Count) for a range of natural language processing tasks.