Definition and Usage – Relating to or occurring in the morning; early. "Harry Truman - like Winston Churchill - was known to take a matutinal shot of whisky. He did it after his regular early-morning walk". Biology Matutinal is a term used in the life sciences, to describe an organism that's only or primarily active in the pre-dawn hours or early morning. The variant term matinal is used apparently only in entomology, often used in literature on the natural history and ecology of bees… (More on Matutinal)