Final answer:
The specific word Bonnie used is not provided in the text excerpts, but she could have used common baseball phrases like 'throw it hard' or 'fastball', both of which suggest throwing the ball with full force.
Step-by-step explanation:
The word that Bonnie likely used to indicate that Matt should throw his baseball as hard as he could is not explicitly provided in the given excerpts. However, based on the context of baseball, a common phrase or word of encouragement intended to communicate that someone should exert their maximum effort, especially in the context of pitching a baseball, might be 'throw it with all your might', 'give it your best shot', 'put your arm into it', or simply 'throw it hard'. In baseball terminology, there is also a specific type of pitch known as a fastball, which is thrown as quickly as the pitcher can manage.
If Bonnie were knowledgeable about baseball and wanted to encourage Matt to use his full power, she might have referenced a fastball or told him to 'fire it in' or 'let it rip'. In the absence of direct information from the texts provided, one might infer such phrases to answer the question.