British Dictionary definitions for phrenologically
(formerly) the branch of science concerned with localization of function in the human brain, esp determination of the strength of the faculties by the shape and size of the skull overlying the parts of the brain thought to be responsible for them
1815, literally "mental science," from phreno- + -logy "study of." Applied to the theory of mental faculties originated by Gall and Spurzheim that led to the 1840s mania for reading personality clues in the shape of one's skull and the "bumps" of the head. Related: Phrenological; phrenologist.