Old and archaic family relationship terms

The MyHeritage.com blog had a post entitled "Avuncles and Niblings: Unusual words for the family." The post was taken from another post in the mental_floss blog with the further title of "11 Little-Known Words for Specific Family Members." You might want to test your knowledge on the following words and then go to the articles for the answers:

• Patruel
• Avuncle
• Niblings
• Fadu
• Modrige
• FŒdra
• Eam
• Brother-uterine
• Brother-German
• Double cousin
• Machetonim

The post with the longer list makes the observation, more than once, that the words are "not in the dictionary." All of the words except, patruel, do show up in the dictionary. I began to wonder what dictionary they were referring to. The simplest way to to find the meaning of any strange word is to do a Google search using the format: "define [enter the unusual word]." This means if I wanted to know the meaning of patruel, I would type in "define patruel." Doing this takes me to an earlier blog post in blog entitled, Words Gone Wild, with an extensive definition. Other results from this simple search give references to the Oxford English Dictionary (OED), which, by the way is what I would call, The Dictionary. The official OED website is a subscription site, but it is possible that your library subscribes. I don't really think the OED wants individual subscriptions, the price is very high for a dictionary website. By the way, even the Old English term was found instantly by Google. 

If you like books, you can also used two that I found interesting. 

Evans, Barbara Jean. A to Zax: A Comprehensive Dictionary for Genealogists & Historians. Alexandria, VA: Hearthside Press, 1995.

and

FitzHugh, Terrick V. H. The Dictionary of Genealogy. Totowa, N.J.: Barnes & Noble, 1985.

Oh, the reason the words may not "show up in the dictionary" you might be using is because some of them are really in Latin or Yiddish or Old English or whatever.