This is the 392nd most frequent German word.
bad
"Bad" in German means "bath" or "bathroom" in English.
In this sentence, 'Bad' refers to a place, specifically a bathroom or a bathing room.
Ich gehe ins Bad, um zu duschen.
I go to the bathroom to take a shower.
Here, 'Bad' is part of a compound noun 'Thermalbad,' referring to a spa or a therapeutic bathing location.
Wir fahren am Sonntag ins Thermalbad.
We are going to the thermal spa on Sunday.
In this example, 'bad' is an adjective borrowed from English, used informally, describing the quality of the weather.