The Collaborative International Dictionary of English v.0.48:
Offset \Off*set"\, v. t. [imp. & p. p. Offset; p. pr. & vb. n. Offsetting.] 1. To set off; to place over against; to balance; as, to offset one account or charge against another. [1913 Webster] 2. To form an offset in, as in a wall, rod, pipe, etc. [1913 Webster]The Collaborative International Dictionary of English v.0.48:
offsetting \off`set"ting\ adj. Compensating for. Syn: countervailing, compensatory, compensative. [WordNet 1.5]