urgent

(fishhook) + (snout) + (bottomheart)
★★★★★
9 strokes

Onyomi

KYUU

Mnemonic

When some CUTE dudes get fishhooks stuck in their snouts while simultaneously having heart attacks, that's pretty urgent.

Kunyomi

いそ*ぐ to rush (usually in the present tense, like this : 急いで!(いそいで!))
★★★★★

Jukugo

急に(きゅうに) xxx

suddenly ★★★★★ KUN ON

急行(きゅうこう)

express train ★★★☆☆
(urgent) + (go) = 急行 (express train)

緊急(きんきゅう) の or に

urgent ★☆☆☆☆
(tense) + (urgent) = 緊急 (urgent)

Synonyms

do it fast!
早速    速やか    急いで   
emergency vs. crisis
救急    危機   
suddenly
いきなり 急に    突然    ふいに