"True, true,—real thanksgiving!" dashed in Mark Clark conclusively, not feeling it to be of any consequence to his opinion that he had only heard about a word and three-quarters of what Joseph had said.
She had expressed to Oak an intention to wait till Boldwood came home before communicating to him her conclusive reply.
…of the stairs, assuring herself by listening to the heavy breathing of her maids that they were asleep, gliding down again, turning the handle of the door within which the young girl lay, and deliberately setting herself to do what, if she had anticipated any such undertaking at night and alone, would have horrified her, but which, when done, was not so dreadful as was the conclusive proof of her husband’s conduct which came with knowing beyond doubt the last chapter of Fanny’s story.
There are no more uses of "conclusive" in the book.