bas·al 
(bāsəl, -zəl)
(bāsəl, -zəl)adj.
1.
a. Of, relating to, located at, or forming a base.
b. Botany Located at or near the base of a plant stem, or at the base of any other plant part: basal placentation.
2. Of primary importance; basic.
basal·ly adv.