Pop music for me means a song that relies on a catchy hooks lyrically and melodically. It has instant commerciality'. They are usually no longer than 3:34 in length. However, would you consider Edgar Winter's instrumental "Frankenstein" (a number one top 40 hit) pop? How about Led Zeppelin's "Black Dog" - a top 40 hit. Or American Pie an 8 minute hit song or a hit jazz instrumental like Chuck Mangione's "Feels So Good"? I think "pop music" is a flexible genre (can incorporate all kinds of styles) that has one thing in common like I said before, "repetitive hooks that happen frequently".
