"Marplots" is an old and rarely used word, which means someone who interferes in the business of others without good intentions. When looking for synonyms of this word, we can use more common expressions such as meddler, busybody, troublemaker, or interferer, all of which imply someone who intrudes where they do not belong. Other possible synonyms include saboteur, mischief-maker, nosy parker, or pest, which suggest a person who causes trouble deliberately or unintentionally. Ultimately, the word is rarely used, and we can convey its meaning using more common vocabulary.