Relating to the essential nature of something; going to the root of the matter.

Most important, chief; fundamental, essential. Cf. primary, adj. 2.

That grounds (in senses of the verb).

Esp. of change or action: going to the root or origin; touching upon or affecting what is essential and fundamental; thorough, far-reaching.

That causes to take root; that establishes. Also: that goes to the root, radical.

Beyond which no advance can be made by investigation or analysis; forming a limit or final stage in respect of nature or quality; fundamental or…

= substrate, adj.

That forms the substratum or base of something; that lies below or at the bottom of something; underlying. Cf. substratal, adj., substrative, adj.

Of, pertaining to, or of the nature of a foundation; fundamental.

Chiefly Theology and Philosophy. Constituting a source or origin; primary, original; basic, fundamental.

Of, pertaining to, or forming a base; fundamental, essential: spec. in Architecture, and in Chemistry. Also applied spec. to an industry which…

figurative. Fundamental.

Of or relating to a substratum; forming a substratum; underlying; fundamental; (now chiefly Linguistics) of or relating to a substrate language.

Constituting a source or centre in or around which something develops or is organized; pivotal, seminal, original. Also: representing that which…

A particular portion of the lower alimentary canal between the pylorus and the anus; = intestine, n.… figurative. Used, chiefly attributive, of an…

= blue-sky, adj. (in various senses).