Pronunciation: (bā'sul, -zul),[key] —adj. 1. of, at, or forming the base.
2. forming a basis; fundamental; basic.
3. Physiol. a. indicating a standard low level of activity of an organism, as during total rest.
b. of an amount required to maintain this level.
4. Med.serving to induce a preliminary or light anesthesia prior to total anesthetization.
5. used in elementary instruction; fundamental: a basal reader.