This is the 944th most frequent Swedish word.
tisdag
Tuesday
The word 'tisdag' is used here as a noun to denote a specific day of the week, Tuesday.
Jag ska träffa Maria på tisdag.
I will meet Maria on Tuesday.
In this example, 'tisdag' specifies a point in time, combined with 'kväll' (evening), to indicate a specific recurring time.
Vi har alltid möte tisdag kväll.
We always have meetings Tuesday evening.
Here, 'tisdagarna' is the plural form of the noun, referring to the occurrence of this specific day weekly.