Support
Root For, Aid
noun, verbal noun
You must respond with aid in order to show your support for someone who needs it. You can usually show your support if you root for them.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
僕は、AKB４８の高橋みなみを応援していました。
I was supporting Takahashi Minami of AKB48.
応援演説で熱心に声を出してたあの応援者は、いったい誰だったんだ？
Who in the world was that campaign supporter who cheered fervently and loudly during the speech?
トーフグ応援団の応援団長に選ばれたが、何をしていいか分からなかったので、前任者の応援を求めた。
I was chosen to lead the Tofugu cheerleading squad, but I had no idea what to do, so I asked my predecessor for advice.