why can you say "yesterday" and "yesteryear" but not "yestermonth" or "yesterhour"?
@Morgane "yesteryear" isn't nearly as common as "yesterday", but in my experience it is said and written. https://books.google.com/ngrams/graph?content=yesterday%2C+yesterhour%2C+yesterminute%2C+yestermonth%2C+yesteryear&year_start=1800&year_end=2000&corpus=15&smoothing=3&share=&direct_url=t1%3B%2Cyesterday%3B%2Cc0%3B.t1%3B%2Cyestermonth%3B%2Cc0%3B.t1%3B%2Cyesteryear%3B%2Cc0
@stylus My world just changed. Thanks a lot ! :3
@stylus You don't say "yesterhour"? I was just thinking how regular a construction this was in English just yesterminute.
@xiombarg with your permission I'll start saying "yesterhour".
@stylus You don't need my permission; it's standard English. I mean, look it up in the OED 4.39 or the 13th edition Merriam-Webster's Collegiate if you don't believe me. </deadpan>
and here's a rare "yestermonth" (1909):
Love, who hath cast out fear, behold
Thy handiwork, how good it is!
This mouth that hath not known a kiss,
This hair that wraps me fold on fold!
But yestermonth, if one had told
Their beauty I had mocked; to-night
They are my coin to buy delight—
My mouth my eyes my arms are gold !
[by Theodosia Pickering Garrison https://books.google.com/books?id=HO00AAAAMAAJ&dq=%22yestermonth%22&pg=PA144#v=onepage&q=%22yestermonth%22&f=false]
@stylus wait is "yesteryear" a thing ??!