firstfruits: the first-ripened produce of the land, owed to God and given to the priests
Firstfruits names the very first crops to ripen in a season, set apart for God before anyone takes a share for themselves. The word grows from a root meaning to be first in producing, the same root behind the words (בכור) for a firstborn child and a firstling animal. The shared idea runs through all of them: whatever comes first belongs to God, and offering that first portion releases the rest of the harvest for ordinary use.
Most often the word refers to the offering itself, the basket of raw first-ripe grain or fruit brought to the sanctuary and handed to the priests. Scholars carefully separate firstfruits from a closely related term (ראשׁית) for first-processed goods like oil, wine, and flour, and from the tithe, which is a fixed tenth. Firstfruits are the just-ripened raw produce, given in no set amount but as the season's earliest yield.
The same word also names the harvest festival built around this offering, the feast later called the Feast of Weeks and once called simply the Day of Firstfruits. And in a few places the word keeps its plainest sense, the first fruit to ripen on a tree or vine, with no offering in view at all.
In its richest setting the offering became a confession that the land is a gift rather than something earned. The worshipper who brought the basket recited the story of Israel's rescue from Egypt, so that handing over the first of the crop became an act of national memory and thanksgiving.