Serial means happening in a series, one after another in a regular pattern. A serial entrepreneur starts several businesses, not at the same time but one after the other. A serial number identifies a specific item in a numbered sequence, like the unique numbers printed on dollar bills or stamped on your bike frame.

The word comes from the way stories used to be published in magazines: in series, with one chapter appearing each week or month. Readers would wait eagerly for the next installment of a Sherlock Holmes mystery or a Charles Dickens novel. Today we still use “serial” this way when we talk about podcasts released episode by episode, or TV shows that tell one continuing story across many episodes.

When something happens serially, it happens in order rather than all together. Your computer processes some tasks serially, completing one before starting the next, while other tasks happen simultaneously.

A serial habit or pattern, like serial lateness, suggests something that keeps happening repeatedly in the same frustrating way.

As a noun, a serial is a story told in parts, released over time.