This term for a word newly coined in the hope it will become accepted may be thought a useful invention, one that’s particularly relevant to World Wide Words — coiners often submit linguistic inventions in the hope that they might be promoted and become a settled part of the language.
The difference between a protologism and a neologism is that the latter has actually been used somewhere, even if only once, while a protologism exists only as a suggestion of a word that might be used.
Wikipedia says that it was coined by Mikhail Epstein, the Professor of Cultural Theory and Russian Literature at Emory University in Atlanta, Georgia, and that it was first used in 2005. It’s from Greek protos, first, plus logos, word, but might equally be taken to be an blend of prototype and neologism.
As protologism is quite often used within the Wikipedia community, it is itself no longer a protologism, but has ascended to the status of jargon.