"Το κλειδί είναι στο υπόγειο."

[ShaoxuanLi]

i noticed the resemblance between υπόγειο και ψυγείο. do they share a common part -γείο; If it is indeed a word root, what does γειο signify?

[nauajos]

υπόγειο < ὑπόγειον < adj. ὑπόγειος (underground) < ὑπόγαιος < ὑπό (under) + γαῖα (earth, land). I don't think this is the case with ψυγείο < ψυγεῖον, which is related to ψύχος (cold).

[nauajos]

By the way, "γαῖα" has become a common prefix in English: "geo-" (geography, geology, etc.)

[Jasutino]

Would you also say this if it were the key TO the basement? Or would you say "Το κλειδί του υπογείου"?

[mizinamo]

I'd probably say Το κλειδί είναι για το υπόγειο "The key is for the basement".