adj.not immediately apparent

"in mathematical science connections are exhibited which...are extremely unobvious"

Unobvious wounds: the suffering of hospice patients.
Attributing Significance to Unobvious Musical Relationships
Identifying unobvious requirements- an exemplar of the Design Science approach
The Everyday Perspective and Exceedingly Unobvious Meaning.
A Method for Identifying Unobvious Requirements in Globally Distributed Software Projects
Description method III-for unobvious hydrophobic state of composite insulators usability of droplet area method
Description Method Ⅰfor Unobvious Hydrophobic State of Composite Insulators——Usability of Contact Angle Method
Description Method Ⅲ—for Unobvious Hydrophobic State of Composite Insulators Usability of Droplet Area Method
Description method II for unobvious hydrophobic state of composite insulators-uncertainty of hydrophobic degree by spray grading met...
Description Method Ⅱ for Unobvious Hydrophobic State of Composite Insulators——Uncertainty of Hydrophobic Degree by Spray Grading ...