SHIGGAION (shĭ-gā'yŏn, Heb. shiggāyôn). A musical term found in the heading of Ps.7.1-Ps.7.17. It may refer to a dithyramb or rhapsody.
International Standard Bible Encyclopedia (1915)
shi-ga’-yon, shi-gi’-on (shiggayon): Occurs in the title of Ps 7, and, in the plural, in the verse introducing Habakkuk’s prayer (Hab 3:1). Derived from a verb meaning "to wander," it is generally taken to mean a dithyramb, or rhapsody. This is not supported by the Greek VSS, but they are evidently quite at a loss.
See Book of Psalms.