A measurable economic factor that changes before the economy starts to follow a particular pattern or trend. Leading indicators are used to predict changes in the economy, but are not always accurate.
The word is also spelled cay and comes from the Spanish cayo. It means a low offshore island, often made of coral. My Muret-Sanders Encyclopaedic (and often Etymologic!) German-English and...
Key is the device used in the identification of insect specimen. For example keys to the insect order is used to identify the insect order. Keys to the families are used to know the family of insects.