Then the chairman threw back his head and roared with laughter. (Para. 13)
Meaning: Then the chairman suddenly moved his head back and laughed in a very loud, deep way.
roar: make a loud, deep sound
The wild animals roared in the woods. 那头野兽在丛林里大吼大叫。
The chairman roared with anger when he heard the bad news. 听到坏消息，主席气得大叫。