patience, perseverance, application, constancy, labor, assiduity, pains, industry, effort, preoccupancy, exertion, preoccupation, sedulousness, persistence.
attention (part of speech: noun)
General Alexis was now studying Mildred Thornton with surprising intentness,
as though he were trying in this moment of their acquaintance to pierce beneath the surface of the girl before him.
- "The Red Cross Girls with the Russian Army", Margaret Vandercook.
Once, when she opened them again, it was to perceive that he was becoming very hot and exhausted, and that Jacob was watching him with such an unpleasant intentness
that she re- closed her eyes that she might not see his face.
- "Benita, An African Romance", H. Rider Haggard.
Franklin's eyes- they had a deepened, ravaged look, but they were still calm- probed hers, all their intentness
now for her.
- "Franklin Kane", Anne Douglas Sedgwick.