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
☆☆ FRET; ANXIETY; NERVOUSNESS Noun 焦燥焦躁，焦虑 sự thấp thỏm, sự nhấp nhổm
☆ BEING FRETFUL; BEING BAD-TEMPERED Noun 神经质神经质，神经过敏 tính cáu kỉnh, sự cáu kỉnh
☆ FRETTING; IMPATIENCE Noun 焦急，焦心 sự bồn chồn, sự lo lắng