A dalliance is a playful flirtation, one that might lead to a casual romance. The king's public dalliance toward the lady in waiting shocked everyone in the court except for the queen.
First appearing in Middle English, the noun dalliance stems from the verb dally, meaning "to waste time, to act playfully, especially in a flirtatious way." Dalliance often describes a casual flirtation — generally something short-term and not very serious. Your aunt may blush when you mention her dalliance with the rugby player she met that time in Dublin. Dalliance can also refer to goofing off when you should be working. Your coworker's continued dalliance can result in missed deadlines.