also: きょうだいあい
noun
sisterly love; affection between sisters
Refers to the bond and love shared between sisters. The reading しまいあい is standard; きょうだいあい is rare and may be confused with 兄弟愛.
彼女たちの姉妹愛はとても強い。
Their sisterly love is very strong.
この小説は姉妹愛をテーマにしている。
This novel has sisterly love as its theme.
兄弟愛 means 'brotherly love' or 'sibling love' and is the common word for sibling affection regardless of gender. 姉妹愛 specifically refers to love between sisters.
Compound of 姉妹 (shimai, 'sisters') and 愛 (ai, 'love'). The reading きょうだいあい is a variant using the reading きょうだい for 姉妹, but this is rare and non-standard.