To be clearly understood, it is important to pronounce words correctly so that people listening to you know what you are saying.
But some words are often pronounced incorrectly (and the only word that can correctly be pronounced incorrectly is "incorrectly" itself!).
Here's some examples:
Laboratory some of these may contain Lab Rats, but that doesn't mean you pronounce it "lab-rat-ory". There's an O in the middle there, and it isn't silent. It's "luh-borra-tree".
Aluminium this word contains 2 "i"s, and they deserve equal pronunciation rights so don't say "aloom-inum", say "alum-in-eeum". Like "condominium" you don't pronounce that "condome-inum" do you?
Nuclear this means "of or pertaining to the nucleus", and nucleus is pronounced "new-clee-us". Nuclear is pronounced "new clear". Not "nukuler". If you can't say it, you shouldn't be allowed to be in charge of anything nuclear... clear?
Specific The S isn't silent. Don't say "can you be more pacific?" unless you are wanting someone to adopt qualities associated with the world's largest ocean.
Pacific Ocean while this is a specific ocean, distinct from the others, you should not pronounce Pacific Ocean as "specific ocean". A "specific ocean" could just as well refer to the Atlantic ocean for example, or the Arctic Ocean, which brings me to...
Arctic both the Cs in this word are hard Cs, pronounced like Ks. It's c-cold in the Arctic, and it's pronounced "ark-tik". Not "art-ic", which leads us neatly on to:
Artic This is short for "articulated truck". So don't say "Ark-tik truck" unless you are talking specifically about a non-articulated truck that operates in the Arctic. If it IS articulated, it would be an Arctic artic.
Ask The order of the letters are very important. Note that the S comes before the K. It isn't nice to "axe" people.
Cavalry it is pronounced "cavul-ry", not "Calvary", which is another name for Golgotha.
Dilate this is pronounced "die late", which is much better than dying early. Which is what your speech might do if you pronounced it "die-uh-late".
Diphtheria this is a tricky one. Almost everyone gets this wrong. I know I usually do. It is important to remember that it isn't written as "dip" followed by "theria". It is written as "diph" followed by "theria", and is pronounced "dif-theory-uh".
Espresso count the Xs. There aren't any! That's why it is pronounced "ess-presso", not "ex-presso" (which conjures up images of an Italian parcel delivery company).
Et cetera another one where we need to count the Xs before we try and pronounce it. There aren't any! That's why we pronounce it "et setter-ruh" (or at least "et setra"), not "ex etra".
February this contains two Rs. Make sure you don't ignore the first one it's "Feb-roo-erry" not "Feb-you-erry".
Jewelry say "jewel" then say "ree". Don't say "joo lerry". If you are British you can get away with saying "joo-el urry".
Ku Klux Klan you'll probably only ever need to say this when denouncing them, but when you do say it, note that the Ku doesn't contain an L. It isn't "kloo", it's "koo".
Library a little like February, there's two Rs in quick succession here. Keep your mouth fit by pronouncing both it's "libe-rarey" not "libe-aree".
Prerogative don't say "puh rogative", give that first R its due!
And I think this one is a good one to close this article with:
Pronunciation this one is commonly mispronounced it isn't "pronounce-ee-ayshun" it's "pronun-seeayshun".
So that's how you'll be pronouncing all those words from now on, capitchee? :)