ETYM Greek phrenos the mind + -logy: cf. French phrénologie.
Study of outline of skull giving supposed indication of mental ability and characteristics.
Study of the shape and protuberances of the skull, based on the (now discredited) theory of the Austrian physician Franz Josef Gall that such features revealed measurable psychological and intellectual traits.
A now abandoned study of the shape of skull as indicative of the strengths of different faculties.