noun a relation that provides the foundation for something.
— synonyms: footing, ground
noun the fundamental assumptions from which something is begun or developed or calculated or explained.
— synonyms: base, foundation, fundament, groundwork, cornerstone
noun the most important or necessary part of something.
— synonyms: base
Examples
“Cars must be checked on a yearly basis.”
“The collection of all possible unions of basis elements of a basis is said to be the topology generated by that basis.”