1. noun /ˈsɪstə,ˈsɪstɚ/
My little sister is an annoying pest.
b) a female member of a religious community; a nun.
Michelle left behind her bank job and became a sister at the local convent.
2. verb /ˈsɪstə,ˈsɪstɚ/
To strengthen (a supporting beam) by fastening a second beam alongside it.
I’m trying to correct my sagging floor by sistering the joists.
Wikipedia foundation.