An adjustable spanner is a tool that is used to loosen and tighten nuts and bolts of various sizes. It is also called a wrench or a crescent wrench. Other synonyms for the term adjustable spanner include adjustable wrench, crescent wrench, monkey wrench, and shifting spanner. Each of these different names may refer to a specific brand or type of adjustable spanner, or they may simply be regional variations in terminology. Regardless of the name, an adjustable spanner is a valuable tool for DIY enthusiasts, mechanics, and tradespeople, as it can be adjusted to fit a wide range of sizes and shapes.