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

其の後[sonoato] after that
已後[igo] after this
一死後[isshigo] after one out (in Baseball)
気後れ[kiokure] nervous
紀元後[kigengo] post-era

空前絶後[kuuzenzetsugo] (so marvelous or horrible that it may be) the first and probably the last
兄後[anigo] elder brother
月後れ[tsukiokure] a month or older
午後[gogo] afternoon
午後中[gogojuu] throughout the afternoon