There are many different ways to say "bid good day." Some synonyms include saying farewell, taking leave, departing, saying goodbye, wishing someone well, parting ways, and saying adieu. These phrases are often used when ending a conversation or encounter, and can be used in both formal and informal settings. It's important to choose the right phrase for each situation, as some may be more appropriate than others. For example, "taking leave" might be a good option for a formal business meeting, while "saying farewell" may be a better fit for a social gathering with friends and family. Whatever phrase you choose, the sentiment is the same: wishing someone a good day ahead.