well-grounded
I
adjective
firm, legitimate, positive, solid, sound, steady, strong, well-based, well-founded
II
index
actual, authentic, believable, cogent, cognizant, convincing, credible, de facto, informed (educated), justifiable, legitimate (rightful), presumptive, provable, rational, solid (sound), sound, stable, tenable, true (authentic), valid
Burton's Legal Thesaurus.
William C. Burton.
2006