blackguard

W. Somerset Maughamの "The Moon and Sixpence" を読んでいます。

物語の語り手はMrs. Stricklandsから、失踪してパリに行ったの夫に会いに行って欲しいと頼まれました。　'VIII' の章から引用します。

'I dare say you'd like me to go', I said to the Colonel, getting up.
'I suppose you've heard that blackguard has deserted her', he cried explosively.
I hesitated.

ColonelはMrs. Stricklandsのbrother-in-lawです。 "blackguard" は失踪した、Mrs. Stricklandsの夫の事をさしていますが、意味を辞書で見ます。

・Oxford English Dictionary: (old-fashioned, British English) ​a man who is dishonest and has no sense of what is right and what is wrong
・Vocabulary.com: In movies, TV shows, and other forms of entertainment, there are often good guys and bad guys. A blackguard is a bad guy. Blackguards are up to no good.
Originally, a blackguard was a type of servant dressed in black, but the meaning evolved to mean a person who is villainous at heart. This is definitely an old-fashioned word you're most likely to see in an older story or play. A blackguard likely won't be guarding anything, but they probably will be doing something evil.

前者の辞書では古語とされていて、戦後から使用頻度が減って来たようですが、後者の辞書の説明にあるようにテレビやドラマではよく使われている言葉の様です。