Synonyms for Basal (same or very similar meaning)
WordNet sense 1 (serving as or forming a base):
baseWordNet sense 2 (pertaining to or constituting a base or basis):
basicWordNet sense 3 (of primary importance):
primaryWordNet sense 4 (basic and fundamental):
essentialWordNet sense 5 (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):
radicalFrom the ODE community, based on WordNetadd/edit