If you pronounce biopic as "BI-opic," you've made a mistake called a misle.
Why 'BI-opic' Seems to Make So Much Sense
But here’s an interesting question: Why are speakers so ready to change their pronunciation? Why is it so obvious that if a word is composed of bio and pic, it should be pronounced BIOpic? How do we know that BIopic is like BIosphere, BIomass, and BIotechnology, and not like biOLogy, biOGraphy, and antibiOTic?
The answer involves two of the many rules that English speakers know without knowing they know them. The first rule is about suffixes. We know that only certain suffixes, including –ic, insist on coming right after a stressed syllable. For example, when you put –ic on the root THORax, you get thorACic, not THORacic. The verb TERRify has stress on the first syllable, but the adjective terrIFic has stress right before the –ic. We don’t say TERRific. In contrast, other suffixes, such as –ful, don’t mess with the stress of their root words. When we attach –ful to the noun WONder, we get WONderful, not wonDERful.
So when we learn that the –ic at the end of BIOpic isn’t a suffix at all, much less one that needs a stressed syllable before it, we’re immediately less likely to put the stress on the OP. And when we learn that BIOpic is a compound, the second rule comes into play: the rule of compound stress. English speakers know that English compound words are almost always stressed on their first element. We have WEB pages, not web PAGES, AIRports, not airPORTS, HOT dogs, not hot DOGS—at least if we’re talking about sausages. If the first element has more than one syllable, the stress still doesn’t get shifted anywhere. So we say PARKing lot, not parkING lot, and MONKey bars, not monKEY bars, and aPARTment building, not apartMENT building. Using the compound stress rule, the word is pronounced BIopic, not bi-O-pic.
Why 'BI-opic' Has Staying Power Even Though It's Wrong
Still and all, the misle biOPic may be gaining more legitimacy than misles such as infrare-d, warp-lanes, and misle. Earlier, I asked why speakers were so willing to change their pronunciation when they learned the etymology of BIopic, but the truth is that not all of them do. To some, biOPic just sounds right, regardless of how it was created. I’ve found several online threads discussing the pronunciation of BIopic, and there is always someone to defend the biOPic pronunciation, even if they know the word is composed of bio and pic. Furthermore, the online Cambridge Dictionary has recordings of both pronunciations, and it says that BIopic is actually the UK pronunciation, while biOPic is the American one. So if you’ve been saying biOPic all this time and the thought of changing is disturbing to you, don’t worry about it too much. As long as you’re not saying bioPIC, you should be fine.
The list of misles: http://chronicle.com/blogs/linguafranca/2011/12/01/beware-the-misles/
Cambrdige Dictionary pronunciations of biopic: http://dictionary.cambridge.org/us/pronunciation/english/biopic