御三時[osanji] three-o'clock snack
三鞭酒[shanpen] champagne
球面三角法[kyuumensankakuhou] spherical trigonometry
胸三寸[munesanzun] heart
元三[ganzan] New Year's period (January 1st to 3rd)

五十三次[gojuusantsugi] the 53 Toukaidou stages
向こう三軒[mukousangen] one's next three neighbors
降三世明王[gouzanzemyouou] Trailokyavijaya Vidya-raja
再三[saisan] again and again
再三再四[saisansaishi] repeatedly

脊髄[sekizui] spinal cord
脊椎[sekitsui] spine
脊椎動物[sekitsuidoubutsu] vertebrate
猫脊[nekoze] bent back
脊広[sebiro] business suit

脊骨[sebone] spine
脊負う[shou] to be burdened with
無脊椎動物[musekitsuidoubutsu] invertebrate
脊柱[sekichuu] spinal column