The term "second-line" can be used to describe a few different things. It can refer to a type of music popular in New Orleans, characterized by a lively beat and the use of brass instruments. It can also be used to describe a backup system or plan, as in "second-line of defense." Finally, it can refer to a procession or parade that follows the main line, often with participants dancing and waving handkerchiefs or parasols. Synonyms for these various meanings include "backup," "reserves," "subsidiary," "parade," "procession," "marching band," "New Orleans jazz," and "street performance".