Definition of "basal"

Basic, elementary; relating to, or forming, the base, or point of origin.  examples

(anatomy) Associated with the base of an organism or structure.  examples

(medicine) Of a minimal level that is necessary for maintaining the health or life of an organism.  examples

(chiefly systematics) In a phylogenetic tree, being a group, or member of a group, which diverged earlier. The earliest clade to branch in a larger clade.  examples

base, bottom, minimum  examples

(anatomy) Any basal structure or part  examples