Being engrossed by something refers to being fully absorbed or focused on a particular activity or task. However, there are a number of antonyms that can be used depending on the context. For example, being distracted or unfocused would be the opposite of being engrossed. Similarly, being bored or uninterested also implies a lack of engrossment. Other antonyms might include being disenchanted, uninvolved, or indifferent. When it comes to the workplace or academic setting, being unproductive or unfocused could also be seen as the opposite of being engrossed in a particular task or project. Ultimately, the choice of antonym depends on context and individual interpretation.