Eta (noun)

1. The seventh letter of the Greek alphabet.
2. A Basque separatist group in Spain that is considered a terrorist organization by the Spanish government and the European Union.

Origin:

From the greek letter η (eta) which represents a speech sound represented by the letter h.

Examples:

1. Eta is the seventh letter of the Greek alphabet.
2. The police arrested several members of the ETA.
3. ETA has been responsible for many bombings and killings.
4. The Spanish government has been trying to eliminate ETA for decades.
5. The ETA has been designated as a terrorist organization by the United States and the European Union.