Genealogy and GEDCOM glossary
A few useful definitions for reading a GEDCOM file or a family tree, in alphabetical order. For a fuller explanation, head to our GEDCOM guide.
Civil record
An official document (birth, marriage, death) issued by a civil authority, often the primary source used to reconstruct a family tree.
Ancestry
All the people an individual descends from: parents, grandparents, and so on into the past.
Collateral line
Relatives who are neither direct ancestors nor direct descendants, such as uncles, aunts or cousins.
Degree of kinship
The genealogical distance between two people, counted in generations back to their most recent common ancestor.
Descent
All the people who descend from an individual: children, grandchildren, and so on into the future.
Filiation
The legal and biological link that ties a child to their parents.
GEDCOM
A standard file format (.ged extension) for exchanging a family tree between software, regardless of which one created it.
Generation
One level of the tree: a generation groups people who sit at the same distance from a reference individual, such as their parents or grandparents.
Individual (GEDCOM)
In a GEDCOM file, each person corresponds to an "INDI" record grouping their identity and the known events about them.
Surname
The family name passed down, traditionally through the paternal line.
Ancestor count
In ascending genealogy, the number of ancestors at a given generation: 2 parents, 4 grandparents, 8 great-grandparents, doubling at every generation back.
Sosa-Stradonitz numbering
A system for numbering a person's ancestors: number 1 is the starting person, the father gets double that number, the mother double plus one.
Root ancestor
The earliest identified common ancestor at the origin of a studied branch or family.
Family unit (GEDCOM)
In a GEDCOM file, the "FAM" record linking a couple to their shared children.
Consanguinity
A kinship link between two people who share one or more common ancestors, for example in a marriage between cousins.
Cousinship
A relationship between two people descended from the same ancestor without being in each other's direct line, such as first or second cousins.
Homonymy
A situation where two distinct people share the same first and last name, sometimes in the same village and era, a frequent source of errors in a family tree.
Pedigree collapse
The reappearance of the same ancestor at more than one point in a person's family tree, usually the result of a marriage between already-related relatives.
Census
A periodic population count, carried out in France since the 19th century, often held in archives and used as a source alongside civil records.
Ten-year index
A French civil-registration index kept since 1792 that groups a commune's births, marriages and deaths by ten-year period, listed alphabetically.
Byname
A traditional nickname attached to a family branch or household, used in some regions to tell apart same-named families within one village.
Parish register
Before civil registration began in 1792, records kept by parishes for baptisms, marriages and burials, the main source for research before that date.
Private baptism
A brief, private baptism given urgently to a newborn thought to be in danger, sometimes noted in registers before or instead of a full baptism.
GEDCOM 7
A newer version of the GEDCOM format, released in 2021, adding support for new data types; adoption is still partial next to version 5.5.1, which remains dominant in exports.