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!"