tap room

[rdmkin]

where does the term "tap room" originate from in respect of a pub tap room

[Quizmonster]

Originally, a taproom was part of a pub where liquor was available 'on tap'...ie what we would now probably call 'on draught'...meaning immediately available via a tap. Of course, we now use the phrase 'on tap' to signify anything that is as readily available.

[Homer55]

I was always told that it originated from men playing dominos, and tapping on the table when they couldnt go.

I could be totally wrong as usual, but its another explanation.