'A year' can be any year without any specification. But 'the year' means a particular/specified year or the one which is already mentioned and thereby known. E.g: In a year there are twelve months. (means any year or all years) I was born in the year 2000. (in that particular year) Grammatically 'a/an' is known as indefinite article and 'the' is definite article. The indefinite article (a/an ...
The comparison with "the second year and the last year" supports plural rather than singular. In that "full" version, each occurrence of the word year clearly relates to a single year.
Unless you're talking about Chinese (or Persian) New Year, the name of the celebration isn't New Year but New Year's Eve, and it happens on the last day of the old year.
The New Year or New Year - English Language & Usage Stack Exchange
In the sentence, The company experienced strong year[-]over[-]year growth., how does the Chicago Manual of Style govern the hyphenation? Part of me believes that it falls under the "phrases,
Under the Chicago Manual of Style, does "year over year" need ...
A year-end review is a review of something held at the end of the year. The year in review could be used as the name of this year-end review, but it can also simply be a phrase describing the period (one year) that is being reviewed. Here's an example of year in review from 1888, which is one of the earliest uses Google Books can find:
"Year-end review" or "Year in review"? - English Language & Usage Stack ...