Between mincha and ma'ariv a few days ago, the shul rav discussed the beginning of this week's parsha, parshat Tzav. He mentioned that the Cohen takes the ashes and places it on the side of the altar. He referred to this process as תרומת הדשן .
I'm a bit confused about this term. Doesn't the word תרומה refer to a "gift" or something given to the Cohen, like the תרומה of produce to be given to the Cohen? What does it mean to give תרומה from the ashes? Who does the Cohen give this to?
Am I misunderstanding some nuance of the meaning of the word, here? Did the rabbi use an incorrect term? Did I incorrectly hear the word? (Sorry, I didn't have time to ask the rabbi afterwards)