Yom Teru’ah
One of the interesting discussions which exists is what does זִכְרוֹן תְּרוּעָה-Zikhron Teru’ah mean (Vayiqra/Leviticus 23:24). Many identify this as being a memorial of some sort. Rabbinic Judaism interprets that when the day falls on Shabbat we only commemorate the sounding of the Shofar, but not actually sound it. This is in opposition to the term יום תרועה “Yom Teru’ah” (Bamidbar/Numbers 29:1), which is understood as a day where we actually use the Shofar.