Low Gothic

Imperial Low Gothic is the common language of the majority of imperial planets and human settlements in the galaxy. The low gothic is common only in the fact that it is a bastardised derivative of the Imperial High Gothic and those knowledgeable of the dead tongues of ancient Terra know them as dialects similar to those of ancient Frank, Britton and Spanian. 
A speaker that is knowledgeable in low gothic will generally be able to decipher and even translate over time local low-gothic dialects, while people used to speak many of these sub-dialects will also develop a knack of expressing themselves everywhere.