ball, sphere
球 centers on a round, three-dimensional object: a ball or sphere. The idea is a solid, curved shape used in play or geometry.
Earth; the globe
baseball
sphere; globe; ball; bulb
table tennis; ping-pong
baseball team
baseball stadium; ballpark
Ryukyu; chain of southwestern Japanese islands comprising Okinawa Prefecture
light bulb
pitching; throwing a ball; bowling (in cricket); pitched ball
base on balls; walk; pass
straight ball (pitch)
hitting (a ball with a bat, racket, golf club, etc.); batting; batted ball; struck ball
balloon (hot-air, weather, etc.); blimp
breaking ball (pitch); curve ball; screwball
ball game (e.g. baseball, tennis, soccer)
white blood cell; leukocyte; leucocyte
throw
pitch that hits the batter
the baseball world
coccus
Earth globe (model); terrestrial globe
pitcher's first pitch (to batter, or in the game)
fastball
(pitcher's) control
球 combines 王 (jade, precious stone) with 求, which likely contributes the sound. The original meaning was a beautiful stone or gem, later extended to a ball or sphere by shape association.
The left side 王 looks like a precious round jewel, and the right side 求 suggests something sought after. Picture a perfectly round gemstone that you want to hold and play with like a ball.
For キュウ, imagine a ball shaped like the letter Q: Q -> キュー, and the round Q-shape cues the reading キュウ.