This is the 593rd most frequent Czech word.
říjnu
"Říjnu" means "October" in the dative or locative case in Czech.
In this sentence, 'říjnu' is the locative case of 'říjen' (October), used to indicate time within the month.
V říjnu slavíme státní svátek.
In October, we celebrate a national holiday.
Here, 'říjnu' is in the dative case, which shows the limit by when something must be done.
Do říjnu musíme odevzdat projekt.
We must submit the project by October.
In this example, 'říjnu' is in the dative case as part of the subject, indicating a descriptive relation about the month.