In building family trees, we define and describe those related to us by blood or marriage. The more precise and unambiguous the terms we use, the better people will understand what we say about families and relatives. However, some of the words are controversial; they have an aggressive or illegal connotation to those new in genealogical studies. If you discovered, for instance, that a blood family relative had a child out of wedlock in the process of your genealogical research, you should put that person on the family tree. Your purpose is to gather information about ancestors, living or dead, and not to judge.

Tables A & B consist of words and their meanings every genealogist needs to know.

Terms and their Meanings
Blood Relationship
Your siblings are your brother or sister
Your uncle is the brother of mother or father
Your aunt is your sister or mother or father
Your cousin is the son/daughter of your aunt/ uncle
Your second cousin is son/daughter of either parent first cousins
Your nephew is a son of your brother/sister
Your niece is a daughter of your brother/sister
Your grandfather is the father of your mother/father
Your grandmother is the mother of your mother/father
Your great-grandfather is the father of your grandparents
Your great-grandmother is the mother of your grandparents
Your grandchildren are your children’s children
Your great-grandchildren are children of your children’s children
Your great uncle is the uncle of one of your parents
Your great aunt is the aunt of one of your parents
Words We Use to Describe or Define Relatives Due to Marriage
Your father-in-law is the father of your spouse
Your mother-in-law is the mother of your spouse
Your sister-in-law is the sister of one’s wife or husband
Your brother-in-law is the brother of one’s wife or husband
Your half-sister/brother is a child from a remarriage of one of your parents
Your stepsister/brother is a child from the previous marriage of stepparent
Your stepdaughter is the child of a spouse from a previous marriage
Your generation consists of yourself, siblings, and cousins.  The next generation
The next generation would be your parents and their siblings.
The first generation. In the United States, first-generation are foreign-born immigrants. The second generation refers to those with at least one foreign-born parent. The third-generation includes those with two U.S. native parents
Great-great-great. We use the word great to describe generation after your father, parents, your grandparents. If you wish to talk about three generations before your grandparents, you will say, great-great-great.  
Foster parents are the parents authorized by state or government to care for or look after children that are not biological to them

Other Words and Their Meanings are as Follows
Genealogy is the study or investigation of ancestry or family history
Ancestry is a history of ancestors, a trail of where your family started and all the descendants that followed.
Stemma is a scroll containing a genealogical list or descendants of one individual
Inheritance is any money or property you receive after the death of a friend, or relative is an inheritance.
Centenarian is at least 100 years old
Domicile is housing that someone is living in
Pedigree is the ancestry or lineage of an individual
Emigrate is to leave one’s country of residence for a new one. If you move to a different country, you emigrate.
Immigrate is to come into a new country and change residency. When a person immigrates, they move to a new country
Transmigrate is to be born anew in another body after death. Your soul, some people believe, will transmigrate into a new body after death.
A patriarchal system is one run by men.
 You can describe your family as matriarchal if it is full of strong women, headed by your feisty grandmother. A group or society is matriarchal when women run it
Familial has to do with all things relating to family
Filial is offspring-related
In perpetuity means for life
A bequest is a gift you receive through a will
Enatic is matrimonial relating to mother
Consanguineous related by blood as a mother and her biological child are consanguineous.
Cognate means related by blood
Sib is someone related by blood or origin; especially on sharing an ancestor with another
Testator. When you make your last will, you are the testator
Intestate is having made no valid will or not disposed of by a legal will
Dowry does a woman bring money to her husband at marriage. In some cultures, the bride or her family pays a certain amount of money or property to the groom when a couple is married. This payment is called a dowry
Nonage any age before the legal age
Matricentric means centered upon the mother
Bar sinister is the status of being born to parents who were not married
Executrix. The feminine form of the word “executor” is “executrix.” It refers specifically to a woman responsible for administering a deceased person’s estate and executing the provisions outlined in the last will.
Probate is an act executed a will correctly
Census is a periodic count of the population
Tutelary. The adjective tutelary describes supervising or guarding something else, like the tutelary duties of a babysitter who makes sure the kids don’t hurt themselves at the playground
Out of wedlock means born when one’s parents are not legally married.
Spinster is an elderly unmarried woman
Progeny means “offspring” or “children.” You and your brothers are the progeny of your parents.