Esp. in legal use: that which constitutes the essential part or aspect of something. Cf. substantial, adj. 9b.

An essential quality (rare); also plural essential points or elements; essentials. Cf. essential, n. 2.

A fundamental quality or attribute determining the nature of something; an essential characteristic or character; essence. Now rare.

Essence, principle, essential principle.

Something belonging to a thing in itself; an intrinsic or essential attribute or quality. Obsolete.