that day
fixed phr..fixed phr.. Used to talk about one specific day in the past or future that has already been mentioned or is understood.
fixed phr.. An adverbial noun phrase used anaphorically or deictically to refer to a specific, contextually-defined day.
I felt very happy that day.
The wedding was beautiful; everyone remembers that day with a smile.
He recalled the armistice with perfect clarity; that day, a profound and unfamiliar silence fell over the trenches.
It points to a specific day already known to the listener or reader from the context.
Contrast 'that day' (a specific, known day) with 'one day' (an unspecified day, often used in storytelling).
I was sick on that day.I was sick that day.Adverbial time phrases like 'that day' or 'yesterday' do not usually take a preposition like 'on' or 'in'.