The best replacement for sister is brother.

The best alternatives to sister are rated as following:
★★★★★  brother
★★★★  nun
★★★  sister
★★  step sister
★  brother wrestling
★  big brother
★  half sister
★  thermoflex
★  daydream nation
  my sister and i
  tipper gore
  brother fight
  little sister
  little brother

Your alternative for sister is not listed? Suggest!
Speaking about sister, one probably shouldn't forget about brother.

Other search terms related to sister and their ratings are:
★★★★★ brother
★★★★ sister
big daddy
You have in mind a companion for sister and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of sister in all years. Click on graph for more.
sister
brother
nun