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 KEY Noun 主要主要 (sự) chủ yếu, chủ chốt
☆ BEING CENTRAL; BEING KEY; CORE Noun 核心的核心的 tính trọng tâm