Cavalier is a term that was originally used to describe a gentlemen companion who was both gallant and chivalrous. These individuals were generally well bred and included military officers and knights. They served as escorts to high society women.
Over time, however, the meaning of the word has changed. According to John Trimble, who defined the term in 5000 Adult Sex Words and Phrases, a cavalier is "a man of great skill in the courting and seduction of females of high position, particularly those who are married." While this definition is widely regarded as obsolete, the word continues to have similarly negative connotations.
A cavalier is a man who acts as a companion or escort for women, but his motivations differ depending on which definition you follow. Historically, a cavalier behaved gentlemanly although he had a presence and charm that made it easy for him to win the ladies over.
In more modern parlance, a cavalier has come to be seen as an individual who acts in his own self-interest with little to no regard of the impact that his choices have on others. This type of cavalier cares little about the emotions of the women that he seduces. While this definition for the term was recorded in the 1960s, it may stem from the Italian use of the word cavalier servant, meaning a married woman’s secret lover.