adj. Of, relating to, or forming a base; fundamental: "Basic changes in public opinion often occur because of shifts in concerns and priorities” ( Atlantic). adj. Of, being, or serving as a starting point or basis: a basic course in Russian; a set of basic woodworking tools. adj. Chemistry Of or relating to a base.adj. Chemistry Containing a base, especially in excess of acid.adj. Chemistry Alkaline.adj. Geology Containing little silica, as igneous rocks.n. An essential, fundamental element or entity: the basics of math. n. Basic training.