Real Dictionary

matriarch
countable noun: A matriarch is a woman who rules in a society in which power passes from mother to daughter.
countable noun: A matriarch is an old and powerful female member of a family, for example a grandmother.

matriarch in American English
a mother who rules her family or tribe; specif., a woman who is head of a matriarchy
noun: the female head of a family or tribal line

matriarch in British English
noun: a woman who dominates an organization, community, etc