latent period

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The interval between exposure to an infectious organism or a carcinogen and the clinical appearance of disease.
• noun The interval between stimulus and response.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the time that elapses between a stimulus and the response to it
• noun the time that elapses before the presence of a disease is manifested by symptoms