"Are sensible of" means to be aware or to perceive something. The antonyms for this phrase would be unaware or ignorant. When someone is unaware, they do not have any knowledge or understanding of a situation. Ignorance, on the other hand, means deliberately avoiding knowledge or not accepting it. Both of these antonyms convey a lack of knowledge or understanding, making the opposite of being sensible of something. It is crucial to be aware of our surroundings to function properly in society, and being ignorant or unaware can lead to misunderstandings and miscommunications. Therefore, it is essential to strive for knowledge and understanding while avoiding ignorance and unawareness.