Aren't these all the same definitions, merely indicating an approximation? "I'm about to arrive" -> "I'm close to arrival but not here right now". "This book

Aren't these all the same definitions, merely indicating an approximation? "I'm about to arrive" -> "I'm close to arrival but not here right now". "This book is about..." -> "This book is roughly this short approximation, because I can't fit the entire synopsis in a sentence,..." "About his person" -> "Close to him, possibly so close as to be carrying it" "He is about" -> "He is somewhere around here, but not in this exact spot" "He is out and about" -> "He is out somewhere in this area" "Gone walkabout" -> "Traveling with no specific destination" "Roundabout" -> "Traffic control method that encourages vehicles to take a more circuitous passage, rather than directly crossing an intersection" The context of the word changes the interpretation, but the essential function of "about" is the same in each case.