Where do words come from? Most words are variations or combinations of words we knew already. This makes them easy to recognize and remember (and makes it easy to figure out where they came from). Some words created from scratch are coined by writers, which aids their popularization (and likewise makes it easier to determine the etymology). But most words of unknown origin have managed to make it into our vocabulary without either of these advantages.
What kind of word can make it against such odds? As you'll see in the list below, many have the advantage of onomatopoeia. But more than that, these are words that you love to know, love to hear, love to say.
I've given the dates of these words -- some from the Oxford English Dictionary, and some from the Merriam-Webster online dictionary (which is where you go if you click the "definition" button); these two sources don't always agree. Some of the dates are obvious, for example, that moola, pizzazz, snazzy, jazz and tizzy are all from the early 20th century.
But there are some surprises. Who'd've guessed that things were nifty as early as 1868? Or that nobody had zits before 1966? Or that you could have taken a brief jaunt as long ago as 1570?
Or that people were nincompoops back in 1676? Actually, I can kind of believe that one ... some things never change ...