Noun and Suffix
とうしゅ
そのダルビッシュ投手の人形はいくらですか？
How much is the doll of the pitcher, Darvish?
二丁目には、田中投手が住んでいます。
The pitcher, Tanaka, lives in 2-Chome.
今日の先発投手は誰になると思いますか？
Who do you think today's starting pitcher will be?
The person who throws with their hand is the pitcher in a baseball game. Other games don't involve throwing with your hand, they've got kicking with feet. So when you picture a hand throwing, picture your favorite pitcher!
This is a jukugo word that uses the on'yomi readings of the kanji. You haven't learned this reading for 手 yet, so here's a mnemonic to help you:
To be a good pitcher, all you have to do is put the ball into the chute (しゅ). Pitchers don't actually throw the ball. There is an invisible pitching chute right on the mound. You slide the ball into the chute and off it goes!