1. of or relating to the Hadean Eon, the earliest division of Earth's history, preceding the Archean Eon
Usage: geology; often capitalized when referring to the geological time period
2. resembling or suggestive of Hades; infernal or hellish
Usage: literary; often capitalized when referring to the underworld

Examples

• The Hadean Eon lasted from about 4.6 billion to 4.0 billion years ago.
• Hadean rocks are rarely found on Earth's surface today.
• Scientists study meteorites to learn about conditions during the Hadean period.
• The planet's hadean landscape was barren and inhospitable to life.
• Early Earth during the Hadean Eon was a molten, violent world.