The Prohibition of Hadash – A Meqori Perspective
What is the world is “hadash”?
The word hadash means “new” and is a reference to “new grain” – in other words, grain that has taken root after the sixteenth day of the Hebrew month of Nisan of one year until after the sixteenth of Nisan of the following year. During that time, the grain which took root is referred to as hadash or “new” and it is forbidden to eat it until after the sixteenth of Nisan.
So, what happens on the sixteenth of Nisan? This is the second day of the week of Pesahwhen the first of the grain offerings for the year – called the Omer – is offered in the Beyth HaMiqdash, or the Temple. In a time like today when there is no Temple, new grain is forbidden for the entire day of the sixteenth, but when the offering is brought in the time of a Miqdash, new grain becomes permitted directly after the Omer is offered during the day of the sixteenth within Jerusalem and surrounding areas, and after halakhic midday (hassoth) in the outlying areas. After either the Omer is offered or midday or the end of the sixteenth of Nisan, the grain is no longer referred to as hadash (“new”), but yashan (“old”), signifying its new permitted status.
From Forthodoxy, here.