Whittle away refers to the gradual reduction or erosion of something. The antonyms of whittle away include building up, constructing, increase, expand, grow, and augment. To build up means to strengthen, enhance or develop whereas to construct means to build or assemble something, such as a structure, systematically. Increase refers to the growth or addition of something, while expanding means to broaden, widen or stretch. Growing means to improve, flourish or advance and to augment means to enhance, improve or intensify. In general, the antonyms of whittle away depict the characteristics of growth, expansion, and improvement.