  Much previous work characterizing language variation across Internet social
groups has focused on the types of words used by these groups. We extend this
type of study by employing BERT to characterize variation in the senses of
words as well, analyzing two months of English comments in 474 Reddit
communities. The specificity of different sense clusters to a community,
combined with the specificity of a community's unique word types, is used to
identify cases where a social group's language deviates from the norm. We
validate our metrics using user-created glossaries and draw on sociolinguistic
theories to connect language variation with trends in community behavior. We
find that communities with highly distinctive language are medium-sized, and
their loyal and highly engaged users interact in dense networks.
