Howdydoing is a casual greeting that is commonly used to ask how someone is doing. However, there are many other synonyms that can be used to express the same idea. Some of the most common ones include: "Hey there!", "What's up?", "How's it going?", "How are you?", "What's new?", "Howdy!", "Hi!", "Hey!", "Hello there!", and "How do you do?". These phrases can be used interchangeably depending on the level of formality and familiarity of the conversation. Regardless of the synonym used, the intention is the same - to greet someone and inquire about their well-being.