1 (wiktionary) 2 (vi.wikipedia) 3 (en.wikipedia) 4 (glosbe)

Core Words Familarize yourself with the 'core words'.
Compounds Expand your vocabulary by studying more complex words built by the 'core words'.
Etymology Explore the origin of the 'core words'.

{n}	lifetime	(duration of the life of someone or something)	Leben {n}, Lebensdauer {f}, Lebenszeit {f}
{n}	lifetime	(informal, hyperbolic: a long period of time)	Ewigkeit {f}