Presumed without analysis.
Self-evident, intuitively obvious.
Based on hypothesis and theory rather than experiment or empirical evidence.
Developed entirely from scratch, without deriving it from existing languages.
In a way based on theoretical deduction rather than empirical observation.
Barely noticeable, not obvious, indistinct.
Tenuous; rarefied; of low density or thin consistency.
Cleverly contrived.
Cunning, skillful.
Insidious.
Hard to grasp; not obvious or easily understood.