Abstract This thesis is a descriptive study of Portuguese loanwords, with a focus on three aspects: the form, meaning, and usage of loanwords. The data for this descriptive analysis are over 300 Portuguese loanwords used in Macao, collected from existing lexicographical work and elicitation sessions with Cantonese-Portuguese bilingual speakers living in Macao. First, I analyze the form of loanwords in the data. Following Tang's (1997) classification of lexical borrowings, I propose a modified classification for Portuguese borrowing in Macao Chinese for this purpose. Second, I study the semantic aspects of Portuguese loanwords. I identify the various semantic domains that are relevant to loans in the data, and also investigate the patterns of semantic change which loanwords undergo in the process of adaptation. Finally, I propose several functions of loanword usage, suggesting that the functions of need-filling and special effects are both important factors that motivate Macao speakers to adopt Portuguese loanwords. The analysis of this thesis shows that loanwords are outcomes of a creative process of linguistic adaptation. This process is influenced by a variety of linguistic and cultural factors ranging from orthographic representation to speakers' interactional needs. This research supports the idea that the study of loanwords can be a rich depository of cultural knowledge, and that there is much to learn from the remarkable influence of Portuguese loanwords on Chinese.