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

外壕[sotobori] outer moat (castle)
塹壕[zangou] trench
内壕[uchibori] inner moat
防空壕[boukuugou] air-raid shelter

掩壕[engou] cover trench
待避壕[taihigou] bomb shelter
塹壕熱[zangounetsu] trench fever