An expression in parentheses:
— His writing was full of parentheticals.

synonym: parenthetical expression.

Qualifying or explaining; placed or as if placed in parentheses:
— Parenthetical remarks.

synonym: parenthetic.

Roget 10: irrelative^†, irrespective, unrelated; arbitrary; independent, unallied; unconnected, disconnected; adrift, isolated, insular; extraneous, strange, alien, foreign, outlandish, exotic.    not comparable, incommensurable, heterogeneous; unconformable etc. 83.    irrelevant, inapplicable; not pertinent, not to the, purpose; impertinent, inapposite, beside the mark, a propos de bottes [Fr.]; aside from the purpose, away from the purpose, foreign to the purpose, beside the purpose, beside the question, beside the transaction, beside the point; misplaced etc. (intrusive) 24; traveling out of the record.    remote, far-fetched, out of the way, forced, neither here nor there, quite another thing; detached, segregate; disquiparant^†.    multifarious; discordant etc. 24.    incidental, parenthetical, obiter dicta, episodic.    ... show more

Roget 228: interjacent^†, intercurrent^†, intervenient^†, intervening etc. v., intermediate, intermediary, intercalary, interstitial; embolismal^†.    parenthetical, episodic; mediterranean; intrusive; embosomed^†; merged.    ... show more