I would try either of these links:http://www.yourdictionary.com
(it is listed among the useful links on this website)http://www.irishmilwaukee.com
(Conradh na Gaelige, Craobh Curtin's website). This one has a short Irish lesson and a few links to other Irish language websites.
I personally would have to know where the "fada" is if there is one in the word because it changes how a vowel is pronounced. If I remember correctly, the "h" slenderizes the "t", either cancelling or making the combination pronunciation -h- instead of -th- (best check either of my sources, just in case I'm mistaken).
Good luck. :)
Phyllis (aka Sidhe Uaine or Gaia Euphoria)