Bryan Garner on judging the utility and quality of neologisms — webinar (web + seminar), simulcast (simultaneous + broadcast), smog (smoke + fog):
The answer is that the entire language community becomes the judge. Once a word acquires general currency, only a hopelessly out-of-touch pedant would take up quixotic arms against it. Through the force of linguistic natural selection, some words win their way. Others don’t.
I must admit, I’ve never been able to say webinar out loud. Some neologisms are best left unsaid.
Update: A neologism should not be confused with a portmanteau. The above words happen to be both. As always, Wordnik can clarify. (thx, jason)