asterisk – Notice the second S. Say /AS-TER-ISK/, not /as-ter-ik/.

candidate – Notice the first d. Say /KAN-DI-DATE/, not /kan-i-date/.

dilate – The word has two syllables, not three. Say /DI-LATE/, not /di-a-late/.

February – Just about everyone I know drops the first r in February. The spelling calls for /FEB-ROO-AR-Y/, not /feb-u-ar-y/.

et cetera – This Latin term is often mispronounced and its abbreviation is frequently misspelled. Say /ET CET-ER-A/, not /ex cet-er-a/. For the abbreviation, write ETC., not ect.

heinous – People unfamiliar with the TV show Law and Order: S.V.U. may not know that heinous has two syllables. (The show begins with this sentence: “In the criminal justice system, sexually based offenses are considered especially heinous.”) Say /HAY-NUS/, not /heen-i-us/.

Illinois – As with Arkansas, the final “s” in Illinois is not pronounced. Say /IL-I-NOY/ (and /Ar-kan-saw/, not /il-li-noiz/ or /ar-kan-sas/). NOTE: Some unknowledgeable folks may still be trying to pronounce Arkansas as if it had something to do with Kansas. The pronunciation /ar-kan-zuz/ is waaay off base.

“irregardless” – See the real word, regardless.

medieval – The word has four syllables. The first E may be pronounced either short [med] or long [meed]. Say /MED-EE-EEVAL/ or /MEE-DEE-EEVAL/, not /meed-eval/.

sherbet – The word has only one r in it. Say /SHER-BET/ not /sher-bert/.

ticklish – The word has two syllables. Say /TIK-LISH/, not /tik-i-lish/.

vehicle – Although there is an H in the word, to pronounce it is to sound hicky. Say /VEE-IKL/, not /vee-Hikl/.

Mischievous – This is the adjective form of mischief whose meaning is “calamity” or “harm.” Mischievous is now associated with harmless fun so that the expression “malicious mischief” has been coined as another term for vandalism. Mischievous has three syllables with the accent on the first syllable: /MIS-CHI-VUS/. Don’t say /mis-chee-vee-us/

niche – The word is from the French and, though many words of French origin have been anglicized in standard usage, this is one that cries out to retain a long “i” sound and a /SH/ sound for the che. Say /NEESH/, not /nitch/.

See more here.