There are many synonyms for the term "one night engagements." Some of the most common include flings, trysts, hookups, one night stands, affairs, and rendezvous. These terms all refer to brief romantic or sexual encounters that typically only last for one night. While these types of relationships are often seen as casual or even taboo, they can provide brief moments of excitement or pleasure for those involved. However, it's important to note that these types of engagements can also come with their own set of risks or consequences, so it's always wise to approach them thoughtfully and with caution.