Blow hard is a phrase used to describe someone who talks in a boastful and pompous manner. There are several synonyms for the phrase that can be used interchangeably, such as braggart, bragger, show-off, and windbag. Braggart implies a person who boasts excessively, while a bragger is someone who brags frequently. Similarly, a show-off is a person who likes to display their abilities or possessions for others to see. A windbag, on the other hand, refers to someone who talks excessively but has very little substance to offer. All these words can be used to describe someone who talks too much about themselves and their exploits.