[Famous Author whose name shall not be in Google Alerts] used it in the nonfiction workshop I attended Saturday. I witnessed twelve workshop participants do a mental double-take because nobody knew what it meant but nobody was gonna admit to it.
And I still don't think she used it quite right; I think she meant "credible" but was so much in love with her Famous Author status that she felt compelled to toss in a few $100 words. Extra value for our workshop tuition, you know.