Essential character (Biol.), the prominent characteristics which serve to distinguish one genus, species, etc., from another. -- Essential disease, Essential fever (Med.), one that is not dependent on another. -- Essential oils (Chem.), a class of volatile oils, extracted from plants, fruits, or flowers, having each its characteristic odor, and hot burning taste. They are used in essences, perfumery, etc., and include many varieties of compounds; as lemon oil is a terpene, oil of bitter almonds an aldehyde, oil of wintergreen an ethereal salt, etc.; -- called also volatile oils in distinction from the fixed or nonvolatile.
Es*sen"tial (s*sn"sjal), n. 1. Existence; being. [Obs.] Milton.
2. That which is essential; first or constituent principle; as, the essentials of religion.
Es*sen`ti*al"i*ty (?), n. The quality of being essential; the essential part. Jer. Taylor.
Es*sen"tial*ly (?), adv. In an essential manner or degree; in an indispensable degree; really; as, essentially different.
Es*sen"tial*ness, n. Essentiality. Ld. Digby.
Es*sen"ti*ate (?), v. t. [imp. & p. p. Essentiated; p. pr. & vb. n. Essentiating.] To form or constitute the essence or being of. [Obs.] Boyle.
Es*sen"ti*ate, v. i. To become assimilated; to be changed into the essence. [Obs.] B. Jonson.
{ Es*soin" (?) or Es*soign }, n. [OF. essoine, essoigne, F. exoine, L. essonia, exonia; pref. ex- (L. ex from) + sunnis, sunnia, sonia, hindrance, excuse. Cf. Icel. syn refusal, synja to deny, refuse, Goth. sunja truth, sunjn to justify, OS. sunnea impediment, OHG. sunna.] 1. (Eng. Law) An excuse for not appearing in court at the return of process; the allegation of an excuse to the court.