Nasalisation is a term commonly used in linguistics to describe the phenomenon of nasal sounds in speech. Synonyms for the word include nasality, nasal quality, nasal tone, and nasal resonance. These terms are often used interchangeably and refer to the same concept - the presence of nasal sounds in speech. Nasalisation occurs when air flows through the nasal cavity during speech production, resulting in the sound being produced through the nose rather than the mouth. This can occur in vowel sounds, such as French "on" and Portuguese "ã", or in consonant sounds, such as the "m" in "moon". Understanding nasalisation is an important aspect of language learning and speech analysis.