There were three changes of state or condition attended with different consequences, maxima, media, and minima. The greatest, capitis deminutio maxima, involved the loss of liberty, citizenship, and family (e.g. being made a slave or prisoner of war). The next change of state, capitis deminutio media, consisted of a loss of citizenship and family without any forfeiture of personal liberty. The least change of state, capitis deminutio minima, consisted of a person ceasing to belong to a particular family, without loss of liberty or citizenship.
Blacks Law Dictionary provides the following definition:
Capitis Diminutio (meaning the diminishing of status) In Roman law. A diminishing or abridgment of personality; a loss or curtailment of a man's status or aggregate of legal attributes and qualifications.
Capitis Diminutio Minima (meaning a minimum loss of status) - The lowest or least comprehensive degree of loss of status. This occurred where a man's family relations alone were changed. It happened upon the arrogation [pride] of a person who had been his own master, (sui juris,) [of his own right, not under any legal disability] or upon the emancipation of one who had been under the patria potestas. [Parental authority] It left the rights of liberty and citizenship unaltered. See Inst. 1, 16, pr.; 1, 2, 3; Dig. 4, 5, 11; Mackeld. Rom.Law, 144.
Capitis Diminutio Media (meaning a medium loss of status) - A lessor or medium loss of status. This occurred where a man loses his rights of citizenship, but without losing his liberty. It carried away also the family rights.
Capitis Diminutio Maxima (meaning a maximum loss of status) - The highest or most comprehensive loss of status. This occurred when a man's condition was changed from one of freedom to one of bondage, when he became a slave. It swept away with it all rights of citizenship and all family rights.
Diminutio. Lat. In civil law. Diminution; a taking away; loss or depravation.
Capite. - Lat. By the head.