  New words are regularly introduced to communities, yet not all of these words
persist in a community's lexicon. Among the many factors contributing to
lexical change, we focus on the understudied effect of social networks. We
conduct a large-scale analysis of over 80k neologisms in 4420 online
communities across a decade. Using Poisson regression and survival analysis,
our study demonstrates that the community's network structure plays a
significant role in lexical change. Apart from overall size, properties
including dense connections, the lack of local clusters and more external
contacts promote lexical innovation and retention. Unlike offline communities,
these topic-based communities do not experience strong lexical levelling
despite increased contact but accommodate more niche words. Our work provides
support for the sociolinguistic hypothesis that lexical change is partially
shaped by the structure of the underlying network but also uncovers findings
specific to online communities.
