ichidan verb, transitive verb
toss one's head; wave a flag; raise one's voice; rouse oneself
Describes a vigorous, energetic action of shaking, waving, or rousing something. Often used with body parts (head, hair), flags, or voice. The core image is 'shaking/rousing something up forcefully'.
彼は髪を振り立てて走り出した。
He tossed his hair and started running.
The players waved flags energetically to cheer.
彼女は声を振り立てて助けを求めた。
She raised her voice and called for help.