Cousin (or "First Cousin":
The son or daughter of an uncle or aunt.

Full Cousin:
The child of your aunt or uncle.

Second Cousin:
People who have the same great-grandparents, but not the same grandparents.

Third, Fourth, and Fifth Cousins:
Your third cousins have the same great-great-grandparents, fourth cousins have the same great-great-great-grandparents, and so on.

Removed: Distant by degrees in relationship; as, a cousin once removed; means from different generations. The words "once removed" mean that there is a difference of one generation. Twice removed means that there is a two-generation difference. etc.

1C1R, 2C2R, etc:
Abrieviations for the various combinations of cousin relationships. 1C1R means First Cousin Once Removed. 2C2R means Second Cousin, Twice Removed, etc.

2G, 3G, etc:
Abrieviations for Second Great, or Great-Great-Grandfather (2G-Grandfather), Great-Great-Great-Grandfather(3G-Grandfather), etc.

Cross, Parallel, and Double Cousins:
Cross cousins are the children of a brother and a sister. Parallel cousins are the children of two brothers or two sisters. Example: Two SMITH brothers marry two JONES sisters -- their offspring will be double first cousins.

Regular first cousins share only one set of common ancestors, while double first cousins share all lineal and collateral relatives. Also, these SMITH-JONES children would be parallel (or ortho) first cousins.

Parent:
One who begets, or brings forth, offspring; a father or a mother.

Father:
One who has begotten a child, whether son or daughter; a generator; a male parent.

Paternal:
Of or pertaining to a father; Received or derived from a father; hereditary; as, a paternal estate.

Mother:
A female parent; especially, one of the human race; a woman who has borne a child.

Maternal:
Of or pertaining to a mother.

Grandparent:
A parent of one's mother or father; grandfather or grandmother.

Grandfather:
A father's or mother's father; an ancestor in the next degree above the father or mother in lineal ascent.

Grandmother:
The mother of one's father or mother.

Great-grandfather & Great-grandmother:
The father of one's grandfather or grandmother. And the mother of one's grandfather or grandmother.

Child:
A son or a daughter; a male or female descendant, in the first degree; the immediate progeny of human parents.

Son:
A male child; the male issue, or offspring, of a parent, father or mother.

Daughter:
The female offspring of the human species; a female child of any age.

Grandson & Granddaughter:
A son's or daughter's son. And the daughter of one's son or daughter.

Sibling:
A person's brother or sister.

Brother:
A male person who has the same father and mother with another person, or who has one of them only. In the latter case he is more definitely called a half brother, or brother of the half blood.

Sister:
A female who has the same parents with another person, or who has one of them only. In the latter case, she is more definitely called a half sister. The correlative of brother..

Uncle:
The brother of one's father or mother; also applied to an aunt's husband; -- the correlative of aunt in sex, and of nephew and niece in relationship.

Aunt:
The sister of one's father or mother; -- correlative to nephew or niece. Also applied to an uncle's wife.

Granduncle or Greatuncle:
A father's or mother's uncle.

Grandaunt or Greataunt:
The aunt of one's father or mother.

Nephew:
The son of a brother or a sister, or of a brother-in-law or sister-in-law.

Niece:
A daughter of one's brother or sister, or of one's brother-in-law or sister-in-law.

Grandnephew & Grandniece:
The grandson of one's brother or sister. And the granddaughter of one's brother or sister.

Relative:
A person connected by blood or affinity; strictly, one allied by blood; a relation; a kinsman or kinswoman.

Relation:
A person connected by consanguinity or affinity; a relative; a kinsman or kinswoman; a person related by blood or marriage.

Relationship:
The state of being related by kindred, affinity, or other alliance.

Affinity:
Relationship by marriage (as between a husband and his wife's blood relations, or between a wife and her husband's blood relations); -- in contradistinction to consanguinity, or relationship by blood; kinship by marriage or adoption; not a blood relationship.

Consanguinity:
The relation of persons by blood, in distinction from affinity or relation by marriage; blood relationship; as, lineal consanguinity; collateral consanguinity.

Family:
People descended from a common ancestor; a person having kinship with another or others; The group comprising a husband and wife and their dependent children, constituting a fundamental unit in the organization of society.

Kin:
Relatives; persons of the same family or race.

Kindred:
Relationship by birth or marriage; consanguinity; affinity; kin.

Kinsman - Kinswoman
A man/woman of the same race or family; one related by blood; a male/woman relative.

Kinship:
Family relationship.

Degree of Kinship:
The level of relationship between two persons related by blood, such as parent to child, one sibling to another, grandparent to grandchild or uncle to nephew, first cousins, etc., calculated as one degree for each step from a common ancestor. This may become important when determining the heirs of an estate when there is no will.

Ascendent/Ascendant/Antecedent:
Someone from whom you are descended but usually more remote than a grandparent. An earlier or higher generation.

Descent:
Properties attributable to your ancestry; the descendants of one individual; one generation of a specific lineage; derivation, as from an ancestor; procedure by generation; lineage; birth; extraction.

Descendant:
A person considered as descended from some ancestor or race. A later or lower generation.

Ancestor:
One from whom a person is descended, whether on the father's or mother's side, at any distance of time; a progenitor; a fore father.

Ancestry:
A series of ancestors or progenitors; lineage, or those who compose the line of natural descent.

Forefather:
One who precedes another in the line of genealogy in any degree, but usually in a remote degree; an ancestor.

Progeny:
Descendants of the human kind, or offspring of other animals; children; offspring; race, lineage.

Progenitor:
An ancestor in the direct line; a forefather.

Generation:
A single step or stage in the succession of natural descent; a rank or remove in genealogy. Hence: The body of those who are of the same genealogical rank or remove from an ancestor; the mass of beings living at one period; also, the average lifetime of man, or the ordinary period of time at which one rank follows another, or father is succeeded by child, usually assumed to be one third of a century; an age.

Genealogy:
An account or history of the descent of a person or family from an ancestor; enumeration of ancestors and their children in the natural order of succession; a pedigree.
Regular descent of a person or family from a progenitor; pedigree; lineage.

Lineage:
Descent in a line from a common progenitor; progeny; race; descending line of offspring or ascending line of parentage.

Parentage:
Descent from parents or ancestors; parents or ancestors considered with respect to their rank or character; extraction; birth; as, a man of noble parentage.

Pedigree:
A line of ancestors; descent; lineage; genealogy; a register or record of a line of ancestors.

Bloodline:
The descendants of one individual; Pedigree; "his entire lineage has been warriors"

Collateral:
Descending from the same stock or ancestor, but not in the same line or branch or one from the other; -- opposed to lineal.

Inlaw:
A relative by marriage.

Brother-in-law:
The brother of one's husband or wife; also, the husband of one's sister; sometimes, the husband of one's wife's sister.

Sister-in-law:
The sister of one's husband or wife; also, the wife of one's brother; sometimes, the wife of one's husband's or wife's brother.

Father-in-law:
The father of one's husband or wife.

Mother-in-law:
The mother of one's husband or wife.

Son-in-law:
The husband of one's daughter.

Daughter-in-law:
The wife of one's son.

Stepparent:
Stepfather or stepmother.

Stepfather:
The husband of one's mother by a subsequent marriage.

Stepmother:
The wife of one's father by a subsequent marriage.

Stepbrother:
A brother by the marriage of one's father with the mother of another, or of one's mother with the father of another.

Stepsister:
A daughter of one's stepfather or stepmother by a former marriage.

Stepchild:
A son or daughter of one's wife or husband by a former marriage.

Stepchildren:
See stepchild.

Stepson:
A son of one's husband or wife by a former marriage.

Stepdaughter:
A daughter of one's wife or husband by a former marriage.

Source: https://www.facebook.com/forum9ja/posts/1583840758344385