Macronucleus, also known as the meganucleus, is a prominent feature found in ciliates, which are a group of single-celled organisms. The term macronucleus refers to the larger nucleus that is responsible for gene expression, metabolism, and cellular function in ciliates. However, there are several synonyms for the word macronucleus. Some of the synonyms include the meganucleus, the macronucleolus, or the micronucleus. Each of these words describes the same structure, but each has a slightly different emphasis or focus. Using synonyms for macronucleus can give scientists a more nuanced understanding of the structures and functions of single-celled organisms.