good day|day|good イディオム
good day|day|good
interj. Hello or goodbye.

Used as a formal greeting or salute when you meet or leave someone during the day.
Miss Rogers said, "Good day!" when she met her friend on the street. Mr. Lee said "Good day!" and left the office.good day|day|good
interj. Hello or goodbye.

Used as a academic greeting or address back you accommodated or leave addition during the day.
Miss Rogers said, "Good day!" back she met her acquaintance on the street. Mr. Lee said "Good day!" and larboard the office. Dictionary