Pahoehoe

Part of speech: noun

Definitions

1. A type of smooth, often glossy lava flow that forms from low-viscosity magma, characterized by its ropy texture
2. This specific volcanic rock formation is known for its fluid-like appearance during eruption
3. It is commonly found in areas of active volcanism, especially in basaltic landscapes, reflecting its basaltic composition

Etymology: Pahoehoe is a Hawaiian word, borrowed into English because Hawaiian is the language of the islands where this kind of lava was first described in detail. The Hawaiian term refers to lava that cools into a smooth, ropy or rippled surface, and English speakers adopted it as a technical name for that texture rather than translating it. In the rock itself, the surface can look like poured syrup or folded fabric, which is why the Hawaiian word fits so well. The contrast with the other common lava type is the useful part. Its rough, jagged cousin, "aa," is also Hawaiian, and geologists adopted both words for the same reason: the islands produce both forms, and the names describe what the eye sees. Pahoehoe forms when lava is hot and fluid enough to spread in sheets, and as its outer skin cools, the still-moving interior pushes it into wrinkles and coils.