The word 'เฉพาะ (châ-phâw)' serves a definitive role in Thai sentences to mean 'only', 'solely', or 'specifically'. This word is usually placed before the noun that it is specifying for. It emphasizes on describing exclusivity and separation, bringing attention to a specific item or instance. It's often used with pronouns or in contexts where the aim is to differentiate a particular entity from all others.