Definition
To do something independently and voluntarily, without being asked or instructed by anyone else.
在没有任何人的指示或要求下主动去做某事；自行决定做某事
He wasn't asked to do so, he contacted the client off his own bat.
他没有被要求这么做，是他自己主动联系客户的。
I didn't expect her to decide to help; she did it off her own bat.
我没想到她会决定帮忙；她是自愿这么做的。
The manager didn’t ask me to write the report, but I did it off my own bat.
经理没有要求我写报告，但我主动写了。