The antonyms for the word "do thoroughly" include "skimp," "neglect," "scrimp," "omit," and "abridge." When one "skimps," they do not give enough attention, effort, or resources to complete a task effectively. "Neglect" means to ignore or fail to care for something, leading to incomplete or substandard results. "Scrimping" involves economizing or cutting corners, leading to a less than thorough outcome. "Omit" means to leave out or exclude, resulting in an incomplete task. Finally, "abridge" involves reducing or shortening a task, leading to a less thorough result. All of these antonyms for "do thoroughly" suggest a lack of care or attention, leading to subpar results.