When it comes to describing someone who is attentive, there are several synonyms that can be used to paint a more detailed picture of their behavior and demeanor. These include observant, responsive, aware, vigilant, alert, mindful, attentive, focused, concentrated, intent, and perceptive. Each of these words conveys a slightly different nuance of attentiveness, with some emphasizing a sense of heightened awareness or preparedness, while others focus on the level of concentration or intent that someone is exhibiting. Ultimately, the key to choosing the right synonym for are attentive is to consider the specific context in which it is being used and the specific qualities that you want to highlight in the individual in question.