Parlous is both a synonym and a derivative of perilous; it came to be as an alteration of perilous in Middle English. (Perilous is derived from the Anglo-French perilleus, which ultimately comes from the Latin word for "danger," perīculum.) Both words are documented in use from at least the 14th century.

What does parlous state mean?

If something is in a parlous state, it is in a bad or dangerous condition. [formal] ...the parlous state of our economy. Synonyms: dangerous, difficult, desperate, risky More Synonyms of parlous. COBUILD Advanced English Dictionary.

What is the difference between parlous and perilous?

As adjectives the difference between parlous and perilous

is that parlous is attended with peril; dangerous; risky while perilous is dangerous, full of peril.