tiresomely long; seemingly without end
"endless debates"
"an endless conversation"
"the wait seemed eternal"
"eternal quarreling"
"an interminable sermon"
having no known beginning and presumably no end
"the dateless rise and fall of the tides"
"time is endless"
"sempiternal truth"
Having no end.
"The endless row of cars stretched all the way to the horizon."
Endless comes from the Old English word endelēas, which combined "end" with a suffix meaning "without." This term has been used in English since Middle English to describe something that goes on forever.