Most inobservant means lacking observation or attentiveness. Antonyms of the word most inobservant are observant, perceptive, attentive, alert, mindful, vigilant, keen, aware, conscious, and observative. Observant means paying attention to surroundings, details, or behavior. Perceptive refers to the ability to perceive subtle details or changes. Attentive means being attentive to detail, while alert means being ready to notice or respond. Mindful refers to the conscious awareness of oneself and surroundings. Vigilant means being alert and watchful. Keen refers to an intense or sharp perception. Aware refers to being conscious or cognizant of something. Observative means being observant or noticing small details.