Not essential to the existence of a thing; not necessarily present, incidental, secondary, subsidiary.

Non-essential; = accidental, adj. 2. Obsolete.

Occurring or liable to occur by the way, or in the course of something else of which it forms no essential part; casual; = incidental, adj. 1. Now…

Having the nature of a logical accident; not affecting the essence, non-essential. Cf. accidental, adj. 1 2.

Of a thing: = accessory, adj. 1.

Non-essential, subsidiary; = accidental, adj. 2 1.

Of a thing: contributing as an adjunct or in a minor way; subsidiary; auxiliary; supplementary. Cf. accessary, adj. 2.

Pertaining as a circumstance; incidental, attendant.

That comes from outside, deriving from an external source; (also) extrinsically added as opposed to essentially inherent; additional.

That comes from outside or from some external source; extrinsically added; extraneous; foreign. Cf. adventitious, adj. 1.

= adventitious, adj. rare after 17th cent.

esp. Of circumstances as opposed to essentials: Adventitious, accidental, incidental or unimportant.

metaphorical Non-essential.

= adventitious, adj. (in various senses).

Occurring or liable to occur in fortuitous or subordinate conjunction with something else of which it forms no essential part; casual.

Of the nature of an increase or augmentation; additional; supplementary; accessory.

Of contingent nature, non-essential; as n. a non-essential.

Not essential.

not included in the essence of some thing.

Attributable to something else as an adjunct; that may be connected to something as a corollary, accompaniment, or consequence.

Separable, non-essential (= dividual, adj. 1).

Not essential, not of the essence of a thing; not necessary or indispensable to the constitution or existence of any thing.

gen. Of, relating to, or situated on a periphery; constituting or characteristic of the circumference or external surface of something; (figurative)…