I was just learning the word for witch:

witch - N. - แม่มด

Syn. :: enchantress; sorceress

The only definition for มด that I can find is ant.

มด - N. - ant

While my literal translation (mother ant) makes it easy to remember, it doesn't make much sense. Does มด have any other meanings?

[definitions from Lexitron]

Yes, มด means Doctor as in witchdoctor.... it's an ancient word from pali language

http://www.royin.go.th/th/knowledge/detail.php?ID=1237

I read the article written by Aj. Chamnong that patri has linked to, but I disagree with some of his analysis. It seems more likely that it simply comes from Khmer. Khmer has the phrase មេមត /mee mʊət/, which corresponds to แม่มด in Thai, with the same meaning. But in Khmer, the word /mʊət/ means "to act in concert, to have a secret understanding; to inform in advance," hence a แม่มด is a female medium, i.e. someone who has secret understanding or advance knowledge regarding spirits.

I don't buy the connection to มตะ meaning "dead" that Aj. Chamnong claims. I wrote about it in more detail on my blog (which I'm told I'm not allowed to link to).

I wrote about it in more detail on my blog (which I'm told I'm not allowed to link to).

You can just let them know to see your URL in your profile, no problems with that.

Interesting.

Follow up question. Is Harry Potter a พ่อมด? and/or a ผู้ที่มีเวทมนตร์?

FYI, new movie, HP5, not good.

Disclaimer: I'm not a Harry Potter fan, just like to go to the movies.

Another question:

Can you use witch แม่มด in the informal English derogatory manner for an old, unpleasant, woman?

(And what about พ่อมด , wizard, for somebody who is really skilled at something?)

Interesting.

Follow up question. Is Harry Potter a พ่อมด? and/or a ผู้ที่มีเวทมนตร์?

Yep. In the Harry Potter books, พ่อมด and แม่มด are used for witch and wizard. I read the first HP book in Thai a few years back. I think "Hogwarts School of Witchcraft and Wizardry" is โรงเรียนคาถาพ่อมดแม่มดและเวทมนตร์ศาสตร์ฮอกวอตส์. It even has its own page on Thai Wikipedia!

I think the word แม่มด in Thai is mostly colored by Hollywood movies--in Aj. Chamnong's article (from 1985, mind you) he mentions how the word แม่มด conjures in people's mind the lotion commercial on TV in which a witch asks her magic mirror a Thai version of "Mirror, mirror, on the wall, who's the fairest of them all?" and the mirror (humorously) answers "ก็สโนไวต์นะซี"--"Snow White, of course!" (I presume it's because she used the lotion being advertised.)

He also mentions that พ่อมด is less common than แม่มด, but I think Harry Potter has probably upended this. His following in Thailand is as devoted as anywhere, if perhaps smaller, and Harry Potter has probably helped to popularize a lot of new (or previously more rare) terms and concepts. Things like "magic wand" ไม้กายสิทธิ์, "invisibility cloak" เสื้อคลุมล่องหน, etc.

Another question:

Can you use witch แม่มด in the informal English derogatory manner for an old, unpleasant, woman?

(And what about พ่อมด , wizard, for somebody who is really skilled at something?)

I don't think either of those uses are idiomatic like in English, no. You might be able to explain what you meant by it and get it to catch on, though.