Mother's cousin is the daughter of menstruation, the family of menstruation or the family of uncle. She is younger than her mother, but they belong to the same generation. Because my mother's cousin is twice as tall as you, you should call her Tang Menstruation, or just call her Menstruation, which will be more cordial. And your mother's cousin should call you nephew or niece.
Written appellation of kinship
Brother's wife and sister-in-law
My brother's wife and daughter-in-law
Sister's husband and brother-in-law
Sister's husband and brother-in-law
Father's brother, sister-in-law, uncle and aunt
Father's sister and brother-in-law, and his aunt and uncle.
Father's brother, sister-in-law, uncle and aunt
Mother's brother and sister-in-law and brother, sister-in-law, uncle and aunt.
Mother's sister-in-law and sister-in-law's menstrual uncle
Brothers' children, nephews and nieces
Sisters' children, nephews and nieces
Brother's grandson and granddaughter
Brother's grandson, nephew, grandson and granddaughter