カバー曲[kabaakyoku] remake of another artist's song (a "cover")
サイン曲線[sainkyokusen] sinusoid
愛唱曲[aishoukyoku] favourite song
委曲[ikyoku] details
一曲[ikkyoku] tune (melody, piece of music)

迂曲[ukyoku] meander
円曲[enkyoku] roundabout way (of speaking or working)
円錐曲線[ensuikyokusen] conic curve
円舞曲[enbukyoku] waltz (composition)
演曲[enkyoku] musical program

悪球[akkyuu] hard ball to hit
逸球[ikkyuu] muffed ball
衛星地球局[eiseichikyuukyoku] (satellite) earth station
眼球[gankyuu] eyeball
気球[kikyuu] balloon

球戯[kyuugi] billiards
球技[kyuugi] ball game (e.g. baseball, tennis, soccer)
球菌[kyuukin] coccus
球形[kyuukei] globular or spherical shape