The phrase "bit-by-bit" refers to a gradual and incremental process. Its antonyms are words that describe opposite meanings, such as sudden, immediate, or abrupt. Instead of slowly, piece by piece, these antonyms imply a quick and decisive approach. For example, words like all at once, in one fell swoop, or overnight convey a sense of immediacy or suddenness. Other antonyms for bit-by-bit may include big picture, broad strokes, or at a glance, which suggest a more comprehensive or high-level approach, rather than a detailed, step-by-step one. Ultimately, the choice between these opposite meanings will depend on the context and goals of the task at hand.