adv. 25B6; adverb
I shall be eternally grateful : FOREVER, permanently, perpetually, (for) evermore, for ever and ever, for eternity, in perpetuity, enduringly; N. Amer. forevermore; informal until doomsday, until the cows come home; archaic for aye.
the tenants complain eternally : CONSTANTLY, continually, continuously, always, all the time, persistently, repeatedly, regularly; day and night, non-stop; endlessly, incessantly, perpetually; interminably, relentlessly; informal 24-7.