A neologism is a newly invented word, whose use isn't yet widespread enough to warrant inclusion in a dictionary.
I enjoy making up words - sometimes to see if they will catch on, sometimes just for the hell of it. Technically, that makes some of them protologisms.
A new word, coined earlier today...
anachrospasm /ənakroʊ'spaz(ə)m/ n. An intensely jarring or unsettling episode of déjà-vu.
Sorry about mixing a Greek prefix with a Latin suffix. There aren't many words that do that.
Andrew Macpherson is a storyteller based in Leeds, West Yorkshire. By day he toils as a web developer, and at weekends he roams the land with The Ladybird Project, an artsy-fartsy band of circus folk. He tweets as @MartianWebDev