posek

noun

1. (Judaism)decisor; legal scholar who decides the Halacha in cases where previous authorities are inconclusive or no halakhic precedent exists.

   “Standard disclaimer.... I am not a posek. Always consult a real posek if you want a real p'sak. Poskim don't waste their time answering Usenet postings. :-)”

   “In other words, like many of the poskim in this camp, Rabbi Avraham Danzig is opposed to cantors who are only interested in the melodies and ignore the content of the prayers.”