I "make up" a lot of words, just for the fun of it and to spice up conversation. I "made up this word for the title of my blog and on a whim decided to Google it. There was only one hit. The word was used once way back in 1921 in a - not too favorable - book review in the Archives of Neurology and Psychiatry.
Here are the pertinent sentences in the review:
"But to him, a book like the present raises somewhat forcibly an underlying question of ideational values. It is a case in which possible benefit to psychopathology or to society seems minute in proportion to the energy systematically and devotedly expended. Purposes of sublimation may have been well served; but not every one's mind endures, St. Antony-like, 'ideationizing' so naked and unashamed."
(The quotes around "ideationizing" were double quotes in the original text, indicating that even the author knew he was simply making up a word.)
Here is the citation:
Association, American Medical. Archives of neurology and psychiatry. American Medical Association, 1921.