It was an earnest, steadfast gaze, but she often doubted whether there were much admiration in it, and sometimes it seemed nothing but absence of mind.
With amazement did she first understand that he believed any apology to be in his power; and steadfastly was she persuaded, that he could have no explanation to give, which a just sense of shame would not conceal.
Mr. Collins received and returned these felicitations with equal pleasure, and then proceeded to relate the particulars of their interview, with the result of which he trusted he had every reason to be satisfied, since the refusal which his cousin had steadfastly given him would naturally flow from her bashful modesty and the genuine delicacy of her character.
She was even sensible of some pleasure, though mixed with regret, on finding how steadfastly both she and her uncle had been persuaded that affection and confidence subsisted between Mr. Darcy and herself.
There are no more uses of "steadfast" in the book.
Show samples from other sources
But then, that’s who Helene is: Her faith is steadfast.
Sabaa Tahir -- An Ember in the Ashes
Moving apace with the river was a long single-file line of men, eyes aimed at their feet, shoulders tense, walking steadfastly nowhere.