There are various synonyms for the phrase "throw by" or "throw away," which means to discard or dispose of something. "Discard" means to get rid of something as unimportant or unnecessary. "Dispose of" also means to get rid of something, but usually in a more formal or official manner. "Jettison" refers to the act of throwing something from a ship or aircraft to lighten the load. "Abandon" means to leave something behind or forsake it. "Ditch" refers to throwing something or someone in a careless or unceremonious manner. "Cast off" means to release something or let it go. All of these synonyms can be used interchangeably with "throw by" or "throw away.