This is the 8975th most frequent Japanese word.
決起
"決起" means "rising up" or "taking action with determination."
Here, 決起 (action or uprising) is used to refer to mobilizing or rallying for a cause.
彼らは正義のために決起を呼びかけた。
They called for action for justice.
In this usage, 決起 (action or uprising) denotes a gathering or meeting organized to motivate or unify participants for a purpose.
決起集会は成功裏に終わった。
The rally meeting ended successfully.
Here, 決起 (action or initiative) is employed to describe an individual's act of inspiring or organizing a group to take unified action.