Distributive-temporal case

The distributive-temporal case specifies when and how often something is done.
In English.
The word 'per' is a Latin preposition which means "through" or "for each", as in per annum, meaning 'for each year'.
In Hungarian.
This case (-nta/-nte) in Hungarian can express how often something happens (e.g. "havonta" "monthly", "naponta" "daily", "telente" "every winter", "reggelente" "every morning"); it can alternate with the distributive case in words of temporal meaning.
In Finnish.
This adverb type in Finnish can express that something happens at a frequent point in time (e.g. "on Sundays" is "sunnuntaisin"), or an origin (e.g. "born in" is "syntyisin"). It is restricted to a small number of adverb stems and nouns, mostly those with the plural formed with an "-i-" suffix. The ending is "-sin".
For example, the root "päivä" (day) has the plural "päivi-", and thus the temporal distributive "päivisin" ("during the days").
The temporal distributive case specifies when something is done, in contrast to the distributive case, which specifies how often something is done, as in regular maintenance. These sentences are a good example: "Siivoan päivisin" vs. "Siivoan päivittäin". The former (temp. dist.) means "I clean by day", implying the cleaning is done in the daytime, whereas the latter (dist.) means "I clean daily", implying that there's no day without cleaning.
If the plural has another form than "-i-", either "joka" (each) or the essive case is used. For example, "uusi vuosi" (New Year) is either "joka uusi vuosi" or "uusina vuosina", respectively.