Of or pertaining to form, n., in various senses. metaphorical. Pertaining to the form or constitutive essence of a thing; essential. Opposed to mat…

That is, constitutes, or involves an essential part, point, or feature; essential, material. Cf. substantive, adj. 3. Now rare.

Constituting, or forming part of, the essence of anything; belonging to a thing by virtue of its essence; necessarily implied in its definition…

Of a quality, attribute, or feature: inherent in the nature or essence of a person or thing; fundamental. Now rare.

That makes a thing what it is; forming an essential part or element; essential.

Forming or producing the essence of a thing.

That constitutes or makes a thing what it is; formative, essential; characteristic, distinctive. Obsolete (or not distinguished from 2.)

figurative. That is essential to the existence of something expressed or implied in the context; constituting or involving an essential part or…

That qualifies (in senses of the verb).

Belonging to the very constitution or composition of anything; forming an essential part or element; essential.

Belonging to the stamina or natural constitution of a person or thing.

That belongs to the essence or intrinsic nature of a thing; essential. Obsolete.