奶 is a polysemous noun with three main meanings: the breast (anatomical), milk (the common liquid), and grandmother (an informal shortening of 奶奶, nǎinai, used in direct address within families). The sense 'milk' appears most often in everyday speech, both by itself and in compounds like 牛奶 and 酸奶. The 'breast' sense is more formal or medical, and the 'grandma' sense is colloquial and usually spoken. This character is also a common component in words related to dairy and nursing, but its standalone noun uses cover these three distinct areas.