Zainab's original name was "Barrah," but it was said' "By that she is giving herself the prestige of piety." So the Prophet ﷺ changed her name to Zainab. (Using translation from Bukhārī 6192)
عَنِ النَّبِيِّ ﷺ أَنَّ زَيْنَبَ كَانَ اسْمُهَا بَرَّةَ فَقِيلَ تُزَكِّي نَفْسَهَا فَسَمَّاهَا رَسُولُ اللهِ ﷺ زَيْنَبَ