What does periculous mean?

Periculous is an archaic or rare English word that means dangerous, risky, perilous, or hazardous, derived from Latin periculum meaning danger. It is not commonly used in modern English, but appears in older literature and scholarly texts. The word periculous is essentially a more Latinate form of perilous, both sharing the same root periculum, which also gives us peril and perilous. In classical usage, periculous meant full of danger or involving great risk, as in a periculous journey meaning a dangerous journey, or a periculous undertaking meaning a risky undertaking. The word is pronounced peh-RICK-yoo-lus, with emphasis on the second syllable. In modern English, you would almost always use dangerous, risky, or perilous instead of periculous, because periculous sounds archaic and might confuse listeners. However, it can be found in historical dictionaries, in translations of Latin texts, and occasionally in legal or theological writing that uses Latinate vocabulary. Some dictionaries label it as obsolete or rare. Its noun form is periculum, meaning danger, and the related noun periculosity means dangerousness, though that is even rarer. So periculous simply means dangerous or perilous, but it is an old-fashioned, scholarly way to say it that is rarely used today, with perilous being the preferred modern equivalent.