noun

The lowest part or edge of something, especially the part on which it rests or is supported.

she sat down at the base of a tree

foundation,bottom,foot,support,prop,stay,stand,pedestal,plinth,rest,bed,substructure

transitive verb

Have as the foundation for (something); use as a point from which (something) can develop.

the film is based on a novel by Pat Conroy

found,build,construct,form,establish,ground,root