In electrical engineering: An arrangement of five induction coils, (four in the shape of a cross, and one rotating about the mid point of its longitudinal axis, in the same plane as the cross) arranged in such a way as to tune or rotate the electrical phase of a signal.

A goniometer is used to rotate the display in old analog Plan Position Indicator. And a real cool technical term: "Would you diddle the goniometer a few degrees? Easy...easy... ARGHHH now you've inverted the phase!"

Go`ni*om"e*ter (?), n. [Gr. angle + -meter: cf. F. goniometre.]

An instrument for measuring angles, especially the angles of crystals, or the inclination of planes.

Contact or Hand, goniometer, a goniometer having two movable arms (ab, cd), between which (at ab) the faces of the crystal]s are placed. These arms turn about a fixed point, which is the center of the graduated circle or semicircle upon which the angle is read off. -- Reflecting goniometer, an instrument for measuring the angles of crystals by determining through what angular space the crystal must be turned so that two rays reflected from two surfaces successively shall have the same direction; -- called also Wollaston's goniometer, from the inventor.

© Webster 1913.