TACK, v.t. [Gr. to set,place, ordain.]1. To fasten; to attach. In the solemn or grave style, this word now appears ludicrous; as, to get a commendam tacked to their sees. --And tack the center to the sphere.2. To unite by stitching together; as, to tack together the sheets of a book; to tack one piece of cloth to another. [In the familiar style, this word is in good use.]3. To fasten slightly by nails; as, to tack on a board or shingle.