The word sister is used to refer to a female with the same parents as another individual. The term sister can also be used to refer to a group, such as a sorority or religion. Sisters are usually referred to as big or little sisters, while the sibling’s wife is referred to as a sister-in-law. A sister with only one parent in common is also referred to as a half or step sister. Similarly, an aunt or parent’s sister is also known as an aunt. Sister is derived from the Latin word sororal, which means “related to a sister”.
The term sister is sometimes used synonymously with the term nun. A Catholic nun, for example, lives an enclosed, semi-cloistered life in a monastery. They profess perpetual, solemn vows and adhere to the evangelistic counsels. Sisters of the Catholic Church engage in various works of mercy and apostolic ministries. A common example of a Catholic religious order is the IHM Sisters of Monroe, Michigan. Although the term “sister” is generally more widely accepted, the term “nun” is still used in the Church for women who profess religious vows.
The Sister Study involves following the health and well-being of the women in a cohort. They complete health updates every year and complete detailed questionnaires every two or three years. The research focuses on the causes of breast cancer in women and what affects their quality of life after the diagnosis. The Sister Study provides a better opportunity to identify risk factors than would otherwise be possible. It also allows for researchers to compare different groups of women in similar environments to determine whether some are more likely to develop the disease than others.