noun
leader of a cheering group; head cheerleader
Refers to the person who leads a cheering squad, often in school sports or events. Can be used for both formal cheerleading teams and informal cheering groups.
彼は応援団長としてチームを盛り上げた。
As the head cheerleader, he energized the team.
応援団長の掛け声で、観客が一体になった。
The cheerleading leader's call united the audience.
Compound of 応援 (cheering, support) + 団 (group) + 長 (leader). The term is straightforward and modern.