As they used underground railroad as the name so that they can be hidden and undisturbed by other people. They had a big list of code words which they used to communicate with each other, without attracting attention of any people outside the organisation. The list along with the meaning of the code word is as follows-
Passenger- the people who were free from the slavery and escaped.
Agents- who helped people escaping the slavery.
Station (the room found by reddit user)- the place where people would wait for the agents.
Station Master- the person who owned the station
Conductor- those who led passengers to a safe place