This post is not intended to be comprehensive, but as a starting point for people just getting into genealogy. If you want a more comprehensive list of abbreviations and terms, I highly recommend checking out this page on Rootsweb for genealogy terms and this page on DNA Geek for genetic genealogy terms.

1C1R – first cousin once removed (the numbers can change -for more information on what a first cousin once removed is, see my post What Is A Cousin?)

NPE – non paternal event (sometimes “not parent expected”). When it is discovered that a parent, usually a father, is not the actual biological parent. This can happen anywhere in our family tree, even going back many generations (although the further back it is, the harder it is to discover). Got concerns about things not being as they should in your tree? Check out my post Is This Normal?

MRCA – most recent common ancestor. The most recent common ancestor of siblings is their parent. For cousins, it’s their grandparents. Of course, siblings also share the same grandparents, so the grandparents are also common ancestors for siblings, but only the parents are the most recent common ancestor

ICW – in common with. Some DNA companies refer to shared DNA matches as ICW DNA matches

GPS: Genealogical Proof Standard. The standard by which genealogists prove what they know about their ancestors. While lawyers have “beyond a reasonable doubt” and the “preponderance of evidence,” we have the GPS. You can read more about proof here

Endogamy – when communities are very insulated, people will eventually be married to people to whom they are related. Eventually, almost everyone in the community is somehow related to everyone else in the community. I talk about endogamy here and here

Pedigree collapse – a pedigree is your direct line of ancestors. Sometimes in your tree you will have people who are already related to each other will get married, which means that instead of expanding at that point the pedigree will collapse. For example, you will normally have 8 different great-grandparents, but, if your parents are cousins, you will only have 6 different great-grandparents. While you will often see pedigree collapse with endogamy, one does not necessarily guarantee the other. You can have a pedigree collapse that is not endogamous and have endogamy without pedigree collapse

For the following DNA terms, I recommend checking out my blog post DNA in a Nutshell for more details:

atDNA – autosomal DNA. DNA that’s found on the 22 autosomes that most people have

mtDNA – mitochondrial DNA: DNA that is found in the mitochondria, passed down from mother to child, used to trace the maternal line

yDNA – DNA from the Y chromosome, which most people assigned male at birth have. Since the Y chromosome is passed from father to son, yDNA is used to trace the paternal line

SNP – single nucleotide polymorphism (usually pronounced snip). Points on our DNA where it is likely to differ from other people’s DNA. See more here

Think there’s an abbreviation or term a beginner genealogist should know? Have a question about one of the abbreviations or terms? Let me know in the comments!