Connotations regarding F grade How is the grade F viewed in US academic system, is it abhorred or people see that grade as any other grade. If a student gets an A retaking that particular course, the previous F grade he got would be overwritten, even though there will be a mark on the transcript.Is there any sort of negative stigma because of that?
As F stands for failing, of course there's a stigma associated with it. How much depends on the course in which it's received. For example, failing freshman biology matters much less if you're in art than if you're planning on applying for medical school. 

Also note that different schools handle repeated courses differently. Some schools count only the last grade, while some count both equally in the final average (a zero plus whatever an "A" grade counts as).