ΚΑΛΗΜΕΡΑ / Καλημέρα (Kalimera) = good morning. This is used from early morning till midday. On the other hand if you use the two words separately Kali (sou /sas) mera = have a good day. This can be used as a parting greeting again till midday. Alternatively also in parting Να έχεις / έχετε μία καλή μέρα (Na eheis / ehete mia kali mera) = May you have a good day.