Lasagna code is a slang term used to describe complicated and convoluted software code that is difficult to understand, maintain and modify. It can lead to bugs and slow down the development process. Synonyms for lasagna code include spaghetti code, which refers to code that is tangled and interconnected; hairball code, which refers to code that is chaotic and hard to work with; and rat's nest code, which implies code that is messy and disorganized. Another common term is legacy code, which describes older code that is outdated and may be difficult to update or replace. These terms all describe the challenges that developers can face when working with complex codebases.