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'.
Wordsense Learn about the wordsenses of the english term.

ETYMOLOGY

KOREAN 3.0 Eng Wordtype Etym. Gb Vie
☆☆ BEING FOR A LONG TIME; BEING FOR A WHILE Noun 一度，一时，一阵子，长时间 một lúc lâu, một thời gian lâu
☆☆ FOR A LONG TIME Adverb 久久，好久好久 một cách lâu thật lâu