Denshi Jisho — Online Japanese dictionary

肝要 かんよう essential; vital; crucial; importance
Common word, Na-adjective, Noun, No-adjective 

You can also

Look up kanji details for 肝要.

Try a Yahoo Jisho search for 肝要 .
Try a Goo Jisho search for 肝要 .
Try a Google search for 肝要 .