The word "riggish" is not common in modern language and has fallen out of use in many places. However, it may still be found in some dialects or older texts. Some synonyms for "riggish" include lewd, licentious, wanton, dissolute, and lascivious. These words describe someone who behaves in an immoral or promiscuous way, often with a disregard for societal norms and values. To some extent, these words convey a sense of irresponsibility and selfishness. It is unlikely that someone would use the word "riggish" in everyday conversation, but these synonyms may be used in its place when describing someone's behavior or demeanor.