Learn Hardcore Polish: Biblioteka jest czynna codziennie oprócz niedzieli. - The library is open every day except Sunday.

czynna means “open” (referring to operating hours). It’s an adjective that modifies biblioteka. Since biblioteka is feminine singular in the nominative case, the adjective must agree: feminine (–a), singular, nominative, hence czynna.

Why do we say jest czynna, and can we omit jest?

jest is the third-person singular of być (“to be”), linking the subject to its predicate. In present-tense Polish, the verb jest is often dropped in such descriptive statements. Both are correct:

With jest: Biblioteka jest czynna…
Without jest: Biblioteka czynna…

What’s the difference between czynna and otwarta?

Both adjectives mean “open,” but:

otwarta (from otworzyć/otwierać) emphasizes the physical act of being opened or unlocked.
czynna (from czynność, “activity”) emphasizes that a service or institution is operating. Libraries, offices or clinics often use czynna in hours announcements.

What part of speech is codziennie, and could we say something else?

codziennie is an adverb meaning “every day.” You could also use the phrase każdego dnia (literally “of each day”), which conveys the same idea but is a bit longer and uses a genitive construction.

What does oprócz mean, and which case does it require?

oprócz means “except for” or “apart from.” It always requires the genitive case. That’s why niedzieli is in the genitive singular (the genitive of niedziela).

Why is it niedzieli and not niedzielę or niedziela?

niedziela is nominative (subject form)
niedzielę is accusative (direct object)
niedzieli is genitive, which is required after oprócz.

Could I use another phrase instead of oprócz niedzieli?

Yes. Common alternatives include:

z wyjątkiem niedzieli (“with the exception of Sunday”) – takes genitive
poza niedzielą (“aside from Sunday”) – takes instrumental (niedzielą)

Do I need a comma before oprócz niedzieli?

No comma is required in the simple schedule phrase. codziennie oprócz niedzieli forms one coherent time expression. You might see a comma for stylistic emphasis (e.g., “codziennie, oprócz niedzieli”), but it’s optional and less common.

Is the word order flexible? Could I start with Codziennie?

Yes. Polish word order is flexible. You could say:

Codziennie biblioteka jest czynna oprócz niedzieli.
Codziennie, oprócz niedzieli, biblioteka jest czynna.
All versions are correct; the original order is simply the most neutral.