reglet

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Architecture A narrow, flat molding.
2. n. Printing A flat piece of wood used to separate lines of type.

Century Dictionary and Cyclopedia

1. n. In printing, a thin strip of wood, less than type-high, used in composition to make blanks about a page, or between the lines of large types in open display. Reglets are made of the width of ordinary text-types, from pearl to great primer. Broader strips of wood are known as furniture.
2. n. In architecture, a narrow flat molding, employed to separate panels or other members, or to form knots, frets, and other ornaments.

Wiktionary

1. n. A sheet metal receiver for the attachment of counterflashing. A reglet may be surface-mounted, inset into a raggle or embedded behind cladding.

GNU Webster's 1913

1. n. A flat, narrow molding, used chiefly to separate the parts or members of compartments or panels from one another, or doubled, turned, and interlaced so as to form knots, frets, or other ornaments. See illust. (12) of column.
2. n. A strip of wood or metal of the height of a quadrat, used for regulating the space between pages in a chase, and also for spacing out title-pages and other open matter. It is graded to different sizes, and designated by the name of the type that it matches.