sì
wife or senior concubine of husbands older brother (old)
elder sister (old)
dì sì
sisters-in-law (old)
various concubines of a husband (old)
Sì Wén mìng
Si Wenming, personal name of Yu the Great 大禹[Da4 Yu3]
Bāo sì
Baosi, concubine of King You of Zhou 周幽王[Zhou1 You1 wang2] and one of the famous Chinese beauties