Merriam-Webster Collegiate Dictionary - basal

 adjective  Date: 1645  1.  a. relating to, situated at, or forming the base  b. arising from the base of a stem ~ leaves  2.  a. of or relating to the foundation, base, or essence ; fundamental  b. of, relating to, or being essential for maintaining the fundamental vital activities of an organism ; minimal a ~ diet  c. used for teaching beginners ~ readers  • ~ly adverb