Methylarginine is a compound of the amino acid arginine that has been modified with a methyl group. There are various synonyms that are used for this term. Some of the common synonyms for methylarginine include arginine mono-, di-, or asymmetric dimethylated (MMA, ADMA) or S-adenosylmethionine (SAM) methylated arginine. These terms refer to the different types of methylarginine that can be formed depending on the location of the methyl group on the arginine molecule. Methylarginine has important roles in biological processes such as protein synthesis and signaling. Understanding the different synonyms for this compound can aid in scientific communication and research related to these important processes.