Vine's Expository Dictionary of NT Words 
"to plunder, spoil," is translated "I robbed" in 2—Corinthians 11:8 . Cp. sulagogeo, "to make spoil of," Colossians 2:8 .
"to give judgment against, to condemn" (kata, "against," and brabeus, "an umpire;" cp. brabeion, "a prize in the games," 1—Corinthians 9:24; Philippians 3:14 , and brabeuo, "to act as an umpire, arbitrate," Colossians 3:15 ), occurs in Colossians 2:18 , RV, "let (no man) rob (you) of your prize" (AV, "... beguile ... of your reward"), said of false teachers who would frustrate the faithful adherence of the believers to the truth, causing them to lose their reward. Another rendering closer to the proper meaning of the word, as given above, is "let no man decide for or against you" (i.e., without any notion of a prize); this suitably follows the word "judge" in ver. 16, i.e., "do not give yourselves up to the judgment and decision of any man" (AV, marg., "judge against").
Webster's Dictionary 
(1): ( v. t.) To deprive of, or withhold from, unjustly or injuriously; to defraud; as, to rob one of his rest, or of his good name; a tree robs the plants near it of sunlight.
(2): ( v. i.) To take that which belongs to another, without right or permission, esp. by violence.
(3): ( n.) The inspissated juice of ripe fruit, obtained by evaporation of the juice over a fire till it acquires the consistence of a sirup. It is sometimes mixed with honey or sugar.
(4): ( v. t.) To take the property of (any one) from his person, or in his presence, feloniously, and against his will, by violence or by putting him in fear.
(5): ( v. t.) To take (something) away from by force; to strip by stealing; to plunder; to pillage; to steal from.
King James Dictionary 
The inspissated juice of ripe fruit, mixed with honey or sugar to the consistence of a conserve.
1. In law, to take from the person of another feloniously, forcibly and by putting him in fear as, to rob a passenger on the road. 2. To seize and carry from any thing by violence and with felonious intent as, to rob a coach to rob the mail. 3. To plunder to strip unlawfully as, to rob an orchard to rob a man of his just praise. 4. To take away by oppression or by violence.
Rob not the poor because he is poor. Proverbs 22 .
5. To take from to deprive. A large tree robs smaller plants near it of their nourishment. 6. In a loose sense, to steal to take privately without permission of the owner. 7. To withhold what is due. Malachi 3 .
Wilson's Dictionary of Bible Types 
Malachi 3:8 (a) Certainly, a part of our possessions and a part of our income belong to GOD. If we fail to give Him that which is His due, He says that we have become thieves, and have taken that which is His to use on ourselves. He indicates in this question that He is surprised that anyone should do such a thing. It shows a terrible condition of the heart when we embezzle GOD's property.