Wiktionary
unobvious
a. Not obvious.
WordNet
unobvious
adj. not immediately apparent; "in mathematical science connections are exhibited which...are extremely unobvious"- A.N.Whitehead [ant: obvious]
Usage examples of "unobvious".
I backed out into the road and left the motor running while I went back up the driveway and placed a few twigs and leaves in unobvious places.
It had created a small scandal, and her new chief of staff, a man of as yet unobvious talents, was barely coping.
To reveal the unobvious would cause more problems than she was willing to deal with.
Ed Bloom has had an amazing knack at seeing the unobvious in the past.
The disused railway line was shown, of course, since the main purpose of a secret map was to show unobvious but practicable routes.