Easton's Bible Dictionary
The corners of fields were not to be reaped, and the sheaf accidentally left behind was not to be fetched away, according to the law of Moses (Leviticus 19:9; 23:22; Deuteronomy 24:21). They were to be left for the poor to glean. Similar laws were given regarding vineyards and oliveyards. (Comp. Ruth 2:2.)
Noah Webster's New International Dictionary of the English Language
1. (v. t.) To gather after a reaper; to collect in scattered or fragmentary parcels, as the grain left by a reaper, or grapes left after the gathering.
2. (v. t.) To gather from (a field or vineyard) what is left.
3. (v. t.) To collect with patient and minute labor; to pick out; to obtain.
4. (v. i.) To gather stalks or ears of grain left by reapers.
5. (v. i.) To pick up or gather anything by degrees.
6. (n.) A collection made by gleaning.
7. (n.) Cleaning; afterbirth.