adjective; synonymous to materterine.
The term materteral in its literal meaning refers to an aunt from the maternal lineage.
A more figurative usage denotes an aunt from either side of the family.
In medical genetics, materteral denotes the genetic relationship between an aunt and her nieces and nephews.
Materteral is the feminine counterpart to avuncular, or having to do with an uncle.
The term comes from the Latin
matertera, or mother's sister, and is in turn derived from the
Latin root
mater, meaning mother.Lest you fear for the sister of the father, Latin once again comes to the rescue. That relationship is the word
amita, which if spelled out on a
Scrabble board that becomes jiggled will sometimes become the word aunt with the intermixing and loss of a few letters.
It is much more obscure in usage than avuncular. It appears originally in the 1823 Oxford English Dictionary and, strangely enough, predates avuncular (which doesn't appear until 1831).
The term is viewed as pedantic and somewhat unwieldy, something found in the arsenal of a word nerd. Of course, to that word nerd the term is just another arrow in his/her quiver.
Sources:
http://www.randomhouse.com/wotd/index.pperl?date=19971119
http://www.medterms.com/script/main/art.asp?articlekey=32723
http://archiver.rootsweb.ancestry.com/th/read/ABOUT-WORDS/2004-03/1080580176