1. the seventh letter of the Greek alphabet (Η, η)
2. estimated time of arrival
Usage: abbreviation

Examples

• The Greek letter eta appears in many mathematical formulas.
• In physics, eta often represents efficiency or viscosity.
• The flight’s ETA is 3:30 PM.
• What’s your ETA for the meeting?
• The package tracking shows an ETA of tomorrow morning.
• Our ETA to the destination is approximately two hours.