Real Dictionary

basal
a horizontal datum line or plane [...]
a specific allowance or selection of food, esp prescribed to control weight or in disorders in which certain foods are contraindicated [...]
a thickness of some homogeneous substance, such as a stratum or a coating on a surface [...]
a thin plate or layer, esp of bone or mineral [...]
an intermediate or middle state, degree, or condition; mean [...]
any flat, curved, or irregular expanse of a surface [...]
at, of, or constituting a base [...]
Basal means relating to or forming the base of something.
external or existing circumstances [...]
the act or an instance of transforming ideas into words [...]
the state or quality of being active [...]