Lissajous figures are the interesting and often intricate patterns that
are traced out when two mutually perpendicular periodic disturbances occur
simultaneously.
The resultant motion can be represented by a repetitive pattern on the
plane containing the two perpendicular directions. The figures depend on the
ratio of the frequencies of the disturbances and the phase difference between
them. French physicist Jules A. Lissajous (1822-80) made an extensive study
of these motions, and these figures are therefore named for him. Lissajous
figures are conveniently displayed on an oscilloscope by applying periodic
electrical signals across its vertical and horizontal inputs. S. BHATTACHARYA
From Groliers