1. (of land or climate) having little or no rainfall, very dry. This is the most common usage and refers to regions with low precipitation, typically characterized by deserts and steppes. Examples: "The Sahara Desert is an arid region." "The climate of the outback is very arid."
2. (of something written or spoken) lacking in interest or excitement; dull and lifeless. This definition focuses on the lack of emotional or intellectual stimulation. Examples: "The lecture was incredibly arid and uninspiring." "The novel's plot was so arid, it felt like a chore to read."
Therefore, "arid" can refer to a physical environment (lack of moisture) or a less tangible quality (lack of interest). The context usually makes it clear which meaning is intended.