A work, such as a work of fiction, published in installments, often numbered and without a specified end.

A publication issued in successive parts, often numbered and with no predetermined end.

(computing, slang) A serial number, esp. one required to activate software.

(UK) A unit of police officers equipped with shields to tackle a riot.

(transitive) to assign a serial number to (especially of aircraft)

Having to do with or arranged in a series.

(of a person) Who performs a specified action or course of action repeatedly or regularly.

Published or produced in installments.

(grammar) Of or relating to a grammatical aspect relating to an action that is habitual and ongoing.