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
☆☆ OBSERVATION; EXAMINATION Noun 观察观察 sự quan sát
☆☆ SURVEILLANCE; OBSERVATION; WATCH Noun 监视监视 sự giám sát
☆ OBSERVATION Noun 观测观测 sự quan trắc