The term "good morning" originated as a polite greeting in English around the 14th to 15th century. It evolved from the earlier Middle English phrase "good morrow," which itself came from Old English "morgen" meaning morning or the first part of the day. The phrase "good morning" was used to wish someone well at the start of the day, becoming popular by the late 14th century as an expression of a favorable or beneficial start to the day. The word "morning" traces back to Old English and Proto-Germanic roots relating to dawn or the early part of the day.
The greeting "good morning" reflects a positive wish for someone's day, with "good" originally meaning desirable or favorable, and "morning" signifying the first part of the day, typically from sunrise to noon. The phrase has been in continuous use in Germanic languages and appeared in English texts from the late Middle Ages.
Additionally, the phrase "top of the morning," often linked to Irish usage, originated in the Victorian era in Britain as a cheerful greeting to wish someone the best part of the morning.
In summary, "good morning" originated in Middle English as "good morrow" around the 14th century, drawing from Old English terms related to the morning time, and was used as a polite, positive salutation to start the day.