To Attack
transitive verb, godan verb
Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means attack and the verb vocab version is to attack.
おそう
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You didn't learn that reading with this kanji, so here's a mnemonic to help you: "You going to attack me or something? Oh so scary you are. Oh so scary. Ho ho ho."
俺は文字通りズボンを下げたところで、突然の激しい腹痛に襲われました。
I was literally caught with my pants down by a sudden, severe attack from a stomach ache.