A good place to start is with the OneLook Dictionary Search. It gives you a choice of dictionaries for the search of a word. Note that some dictionaries also give variant pronunciations.	If you like to look other things up, go to 1000dictionaries. Scroll down to find medical and other language online dictionaries. (There's a lot of advertising, but it's a good online reference.)
nuclear = NEW-clear When did it get to be three incorrect syllables? After the 2000 presidential election? Check out an argument here at the Word Detective site.	Check the American Heritage audio pronunciation of nuclear here.
Heteronyms. There's a new word. It turns out, however, that there are a bunch of them. An example is combat. When you're in COMbat, you comBAT. It's the same spelling, but a different pronunciation. Please check out the Fun with Words site for more examples, as well as more interesting pages on words.	Asterisk. It’s the star symbol in star-dot-star (*.*) that’s come into its own with computers. It’s pronounced ASS-ter-isk, not ASS-ter-ick.
affluent = AFFluent   Except when it doesn't. Please check out this link.    The same with INfluence vs. inFLUent. Who knows?	PreVENtive vs. PreVENTative   According to the Merriam-Webster Dictionary on the Web, the first is correct. The definition of preventative is preventive, so it’s not the preferred pronunciation.   I’d venture to guess the same is true for orient and orientate because there’s no thesaurus entry for the latter.
accessory = akSESSory   Why are they saying assSESSory all over the tube?	Mirror and Mere   How come so many people pronounce these words the same way? Did the wicked stepmother in Snow White really say, "Mere, mere, on the wall. . ."?
In-den-ta-tion. Four syllables. It's not indention.	AdviSe vs. AdviCe   When you ask for advice, it's nice to find someone to advise you.
Sewer. It occured to me that this is an interesting word. You say it one way when you're describing someone who uses a needle and thread and pronounce it a different way when it's a messy hole in the ground.	More to come. . .