What declension is mater?

Mater, matris, is a feminine third declension noun. I hesitated for a second because I thought this might be a trick question, but what the heck ...

Mater,matris reminded me of "matriculate", as to become enrolled in a college that becomes your "alma mater."
I was surprised to find that the derivation is not as direct as I thought. Matrix is ancient word for womb, currently for a list. So matriculating is just getting your
name on a list. Nothing parental except the big bills for
papa to pay.

a college that becomes your "alma mater."

which is to say, your foster mother or wet nurse. And after suckling at the breast of knowledge, you become an alumnus/alumna - foster child.

which is to say, your foster mother or wet nurse. And after suckling at the breast of knowledge, you become an alumnus/alumna - foster child

Alumnus and alma are both from the PIE root *al- 'to nourish' which gives us English old, as well as Latin adultus and adolescens.

http://www.bartleby.com/61/roots/IE11.html

But "prolix" didn't fit where I thought it might.
prolix

SYLLABICATION: pro·lix
PRONUNCIATION: pr-lks, prlks
ADJECTIVE: 1. Tediously prolonged; wordy: editing a prolix manuscript. 2. Tending to speak or write at excessive length. See synonyms at wordy.
ETYMOLOGY: Middle English, from Old French prolixe, from Latin prlixus, poured forth, extended.
OTHER FORMS: pro·lixi·ty (-lks-t) —NOUN
pro·lixly —ADVERB

*al- 'to nourish' which gives us English old, as well as Latin adultus

And adulter?

Adulter is supposed to be from the same root as Latin ulter 'opposite' and ille 'that' (from Old Latin ollus, *ol-no-s), olim 'once'; Old Irish oll 'big, extensive, broad'.

Wow, that root is all over the place in terms of meaning. "Oll-" is still used in Irish as a modifying prefix: "ollscoil" - "university", "ollmhargadh" - "supermarket".

Anyhow, interesting to learn that adults and adulterers have nothing in common!

Except that you would hope (devoutly) that all adulterers are adults.

I thought I'd posted the answer to Faldo's original query shortly after he'd posted it, but for some reason it didn't stick. I agree that it's 3rdD Fem, but, like jheem, I assumed it was a trick question.

So ... Faldo, whyinole didn't you just look it up? [goofy smiley emoticon-type emoticon]

whyinole didn't you just look it up

perhaps he has an ulterior motive?

It wasn't a trick question. The reason I didn't look it up was that I was at work and the onliest Latin references I know on the web assume you already know the declension. The reason I asked was for an answer to the question, 'What is the plural of alma mater?' By the time I got the answer to my question, the answer, 'almae matres,' had already been posted in the original forum.