Denshi Jisho — Online Japanese dictionary

襲う おそう 1: to attack; to assail; to make an assault; to strike; to hunt down;
2: to succeed (someone in a post, role, etc.);
3: to make a sudden visit
Common word, Godan verb with u ending, Transitive verb 

You can also

Look up kanji details for 襲う.

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