A senior or superior; a person of rank or dignity.

One of a board or body of municipal officers next in order to the mayor and having a legislative function. They may, in some cases, individually exercise some magisterial and administrative functions.

Derived from O.E. ealdorman and surviving in urban usage to describe the holder of a senior civic office. Two main usages are (I) the chief officer of a guild: occurs in the earlier Middle Ages and later in surviving merchant guilds; (II) the member of a town council, particularly an upper council: increasingly common in the later Middle Ages, probably under London influence. (Reynolds, Susan. An Introduction to the History of English Medieval Towns, 197)

An Alderman is an elected Member of the Court of Common Council, as well as a Member of the Court of Aldermen. On election, an Alderman also becomes a Justice of the Peace (JP) for the City. Each City ward elects just one Alderman.

a member of a municipal legislative body (as a city council); "aldermen usually represent city wards"

a member of a municipal assembly in a town or city, explains Wikipedia

n. A member of a municipal legislative body, who usually exercises also certain judicial functions.

Assistant to the mayor.

An alderman is a member of a municipal assembly or council in many jurisdictions. The title is derived from the Anglo-Saxon position of ealdorman, literally meaning "elder man," and was used by the chief nobles presiding over shires.