day vs morning

day and morning both are nouns.

Word	Noun	Adjective	Verb	Adverb
day	Yes	No	No	No
morning	Yes	No	No	No

day (noun)	morning (noun)
a period of opportunity	a conventional expression of greeting or farewell, used to wish someone a good morning
time for Earth to make a complete rotation on its axis	the earliest period
a day assigned to a particular purpose or observance	the time period between dawn and noon
the time after sunrise and before sunset while it is light outside	the first light of day
a point or period in time
the recurring hours when you are not sleeping (especially those when you are working)
an era of existence or influence
the time for one complete rotation of the earth relative to a particular star, about 4 minutes shorter than a mean solar day
the period of time taken by a particular planet (e.g. Mars) to make a complete rotation on its axis