V pondělí pracuji celý den.

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Breakdown of V pondělí pracuji celý den.

• den: the day
• celý: all
• v: on

Questions & Answers about V pondělí pracuji celý den.

Why is it v pondělí and not something like na pondělí if the meaning is “on Monday”?

In Czech, v literally means in, but with days of the week it corresponds to English on:

• v pondělí – on Monday
• v úterý – on Tuesday
• v pátek – on Friday

So the natural way to say “on Monday” is v pondělí, not na pondělí.

Na + day is used for different meanings, for example:

• Mám to naplánované na pondělí. – I have it planned for Monday.
  (a deadline / target day, not just “on Monday”)

So for simple time expressions “on Monday”, “on Tuesday”, you use v + [day].

What case is pondělí in, and why doesn’t it change form?