sobrina
Could not find sobrinarum in Logeion dictionaries.
sobrinarum Noun: feminine genitive plural of sobrina
sobrīna, ae, f. (sobrinus, w. vgl.), zweites Geschwisterkind, Muhme, Plaut. Tac. u. ICt.
~a, -e, i. filia sororis
sōbrīna, (14) æ, f. , cousine germaine : Tac. Ann. 12, 6.