1. Latent period (syn: latency): Delay between exposure to a disease-causing agent and the appearance of manifestations of the disease. After exposure to ionizing radiation, for instance, there is a latent period of five years, on average, before development of leukemia, and more than 20 years before development of certain other malignant conditions. The term “latent period” is often used synonymously with “induction period”; that is, the period between exposure to a disease-causing agent and the appearance of manifestations of the disease. It has also been defined as the period from disease initiation to disease detection.
Last JM: A Dictionary of Epidemiology, 2nd ed, International Epidemiology Association, 1988; pg 72.

2. Aron JL. Mathematical modeling: the dynamics of infection
Aron JL. Mathematical modeling: the dynamics of infection. In: Infectious Disease Epidemiology, 2nd ed (Nelson KE, Williams CM, eds), 2007; pg 183.