"a basic fact"; "the basic ingredients"; "basic changes in public opinion occur because of changes in priorities"
is similar to
serving as or forming a base
"the painter applied a base coat followed by two finishing coats"
is similar to
of or being the essential or basic part
"an elementary need for love and nurturing"
is similar to
being or involving basic facts or principles
"the fundamental laws of the universe"; "a fundamental incomatibility between them"; "these rudimentary truths"; "underlying principles"
is similar to
fundamental
"the grassroots factor in making the decision"
is similar to
arising from or going to the root or source
"a radical flaw in the plan"