gen. That which gives a thing its character; that which constitutes the essence of a thing; the essential part, essence.

The main or most important ingredient or element, to which other things are added or from which another thing is derived.

figurative. The centre, core, essential part, etc., of something; cf. marrow, n.1 3.

The fundamental constituent or the essential part of any thing. Obsolete.

gen. The substance of a thing. Obsolete.

The main constituent, fundamental ingredient.

loosely. The most important indispensable quality or constituent element of anything; the specific difference. of the essence (of): indispensable…

A substance which forms the basis of something; a fundamental constituent. Obsolete.

The lowest level or foundation of something; the underlying core, the essence; ‘bedrock’. Also (esp. in later use): the hard facts, reality. Now rare.