Usage patterns
確固たる意志an unshakeable will
He entered the negotiations with an unshakeable will.
確固たる信念a firm, unwavering belief
She continues her research guided by a firm, unwavering belief.
確固たる地位を築くto establish a firm, secure position
The company established a firm position within the industry.
確固とした自信を持つto have firm, unshaken confidence
He always speaks with firm, unshaken confidence.