Necessary, essential for life or some process.
Elementary, simple, fundamental, merely functional.
Of or pertaining to a base; having a pH greater than 7.
Unremarkable or uninteresting; boring; uncool.
An elementary building block, e.g. a fundamental piece of knowledge.
A necessary commodity, a staple requirement.
Basic training.
Living one's life opposing or eschewing the use of substances such as alcohol, tobacco, and drugs.
A flat, rectangular tool used to draw, cut or check the straightness of straight lines.