Source : Webster's Revised Unabridged Dictionary (1913)

Basal \Ba"sal\, a.
   Relating to, or forming, the base.

   {Basal cleavage}. See under {Cleavage}.

   {Basal plane} (Crystallog.), one parallel to the lateral or
      horizontal axis.

Source : WordNet®

basal
     adj 1: especially of leaves; located at the base of a plant or
            stem; especially arising directly from the root or
            rootstock or a root-like stem; "basal placentation";
            "radical leaves" [syn: {radical}] [ant: {cauline}]
     2: serving as or forming a base; "the painter applied a base
        coat followed by two finishing coats" [syn: {base}]
     3: of primary importance; "basic truths" [syn: {basic}, {primary}]