The term "onenighters" is often used to describe a casual sexual encounter that happens only once. However, it may be considered derogatory or offensive in some contexts. Synonyms that may be used instead include "fling," "casual hook-up," "one-time affair," or "one-night stand." These terms imply a brief and non-committal sexual encounter, without the negative connotations that may be associated with using the term "onenighters." It is important to communicate intentions and boundaries clearly in any type of romantic or sexual encounter to ensure that all parties involved feel respected and comfortable.