Longman Dictionary of Contemporary English
Wiktionary
a. 1 (context of a person English) Having extensive knowledge of a subject 2 (context of an argument etc English) Based on good judgment and solid reasoning
WordNet
Usage examples of "well-grounded".
The result of the action was a well-grounded belief that in daylight there was very little chance of the Boers being able to carry the lines.
But John Mangles succeeded, after some persuasion, in calming their well-grounded indignation.
His bitter and at the same time well-grounded and philosophical dislike of the conquering race is well expressed in a speech made before the purely Indian council before referred to, upon the Powder River.
However any of our present institutions may have begun, it can only, they think, have been preserved to this period of advanced civilisation by a well-grounded feeling of its adaptation to human nature, and conduciveness to the general good.
Sheldon saw that the Googles watched intently, but none of it made much sense to him, well-grounded as he was hi alien ritual habits.
But from the standpoint of theoretical logic it must be regarded as a prejudice, not as a well-grounded theory.
Early on I read Alfred North Whitehead and Bergson and became well-grounded in process philosophy.