'Fast' in the Bible

I know where thou dwellest, where the throne of Satan is; and thou holdest fast my name, and hast not denied my faith, even in the days in which Antipas my faithful witness was, who was slain among you, where Satan dwells.

but what ye have hold fast till I shall come.

I come quickly: hold fast what thou hast, that no one take thy crown.

And after this I saw four angels standing upon the four corners of the earth, holding fast the four winds of the earth, that no wind might blow upon the earth, nor upon the sea, nor upon any tree.