importunate · adjective, noun1
First attested in 1477, in Middle english; from Latin importūnus + -ate (adjective-forming suffix), modelled on Middle French importuné. By surface analysis, importune + -ate (compare inopportune). The noun was substantivized from the adjective, see -ate (noun-forming suffix).
importunate · verb2
First attested in 1574; adapted borrowing of French importuner (“to bother, disturb”), see -ate (verb-forming suffix).
Etymology from Wiktionary, CC BY-SA 4.0.