The word Ethereum / Ether / ETH is owned by the Ethereum Foundation, to my understanding. If other domains out there exist with "ETH" etc in it, maybe they have permission (I don't know). If you're in the clear and I'm being overly paranoid, offers accepted...cool domain
https://ethereum.org/en/terms-of-use/
Trademarks
The Foundation name, the terms Ethereum Switzerland, Ethereum Asia, the Foundation logo and all related names, logos, product and service names, designs and slogans are trademarks of the Foundation or its affiliates or licensors. You must not use such marks without the prior written permission of the Foundation. All other names, logos, product and service names, designs and slogans on this Websites are the trademarks of their respective owners