Devarim 24:21

לא תעולל [WHEN THOU GATHEREST THE GRAPES OF THY VINEYARD] THOU SHALT NOT GLEAN IT — i.e., if you find tender grapes in it, thou shalt not take them away. And what are עוללות? Clusters which have neither כתף, “arms” nor נטף “drippings” If, however, they have one of these, then it belongs to the owner of the vineyard (not to the poor) (Mishnah Peah 7:4). (Cf. Rashi on Leviticus 19:10 and our translation and Note thereon). — I have seen the following in the Talmud Yerushalmi Peah 7:4: What is כתף? Where the branches lie one upon the other: whilst נטף are those which hang down directly from the central stem.

כִּ֤י תִבְצֹר֙ כַּרְמְךָ֔ לֹ֥א תְעוֹלֵ֖ל אַחֲרֶ֑יךָ לַגֵּ֛ר לַיָּת֥וֹם וְלָאַלְמָנָ֖ה יִהְיֶֽה׃

When thou gatherest the grapes of thy vineyard, thou shalt not glean it afterwards; it shall be for the stranger, for the fatherless, and for the widow.