par·en·thet·i·cal
[ˌperənˈTHedək(ə)l]
ADJECTIVE
relating to or inserted as a parenthesis.
“ignore the parenthetical remarks that pockmark every page”
synonyms:
incidental · supplementary · by-the-way · by-the-by · in parentheses · parenthetic · in brackets · explanatory · qualifying · inserted · interposed · extraneous
ORIGIN
late 18th century: from parenthesis, on the pattern of pairs such as synthesis, synthetic.
Mws R Writings 