1Adhering or tending to adhere; adhesive; associated. rare after 18th century.
2Of a negative particle: modifying the meaning of an adjacent word such that the two words may function as a single lexical unit expressing negation.
Mid 18th century; earliest use found in Henry Fielding (1707–1754), author and magistrate. From classical Latin adhaerēscent-, adhaerēscēns, present participle of adhaerēscere to stick, adhere, or become attached (to), to stick close (to a person or place) from adhaerēre + -ēscere.