Hypethral is an adjective that means ‘having no roof or open to the sky.’

The Greek prefix H-Y-P-O means ‘under.’ When combined with the Greek word aither (EYE there) which means ‘air,’ we get a word that means under the air or heavens.

I’m not sure whose brilliant idea it was to build a hypethral arena in Seattle, but they must not have been aware of the weather here. Having a roof would actually be a good idea in a place that rains all the time.