Chimerical

The constant anxiety in which he lived, however chimerical the cause of it might be, was evidently having a serious effect upon his health.

a chimerical goal

"Yes; I have a turn both for observation and for deduction. The theories which I have expressed there, and which appear to you to be so chimerical, are really extremely practical—so practical that I depend upon them for my bread and cheese."

With his head bent, and his big feet spread apart, he began explaining his reasons for thinking the abbé’s plan chimerical.

"You are the most charming person in the world. You are invested with a perfect halo of delight," exclaimed Henrietta. "Miss Churchill has some chimerical notion of honour in her head, but that is over now; your information does not leave a single obstacle in the way of the most perfect happiness that ever wound up a fairy tale...