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

金糸雀[kinshijaku] canary (esp. the island canary, Serinus canaria)
燕雀[enjaku] small birds
黄雀[koujaku] tree sparrow (Passer montanus)
欣喜雀躍[kinkijakuyaku] jump up for joy
孔雀[kujaku] peafowl (inc. the male peacock, female peahen, and young peachick)

孔雀石[kujakuseki] malachite
孔雀妙王[kujakumyouou] Mayuri Vidya-raja
四十雀[shijuukara] great tit (Parus major)
雀の涙[suzumenonamida] drop in the bucket