Cannon
noun
A big cannon is... wait for it... just a cannon. I guess all cannons are big, right? At least when you compare them to guns.
たいほう
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
大砲がズドーンと鳴り響き、男は三人の子どもたちを残したまま逝ってしまいました。
The cannon went off with a bang and the man passed away leaving three children behind.