Scientifically, gray or white hair is referred to as what?

Gray or white hair is scientifically referred to as canities. This term specifically describes the condition of hair losing its pigment, leading to a gray or white appearance. The process of canities occurs as the hair follicles produce less melanin, the pigment responsible for the color of hair.

The other terms listed do not specifically refer to gray or white hair in the same context. Albinism is a genetic condition that results in a lack of pigment in the skin, hair, and eyes, but it encompasses a broader spectrum of characteristics beyond just hair color. Achromotrichia refers generally to the absence of color or pigment in hair but is less commonly used and does not specifically denote the natural graying process that occurs with aging. Leukotrichia can refer to white hair but is often used to discuss hair affected by specific conditions rather than the general phenomenon of gray or white hair due to aging.

Thus, canities is the precise term that captures the essence of hair turning gray or white, making it the correct answer.