Snowball is a small string processing language for creating stemming algorithms for use in Information Retrieval, plus a collection of stemming algorithms implemented using it.
The Snowball compiler translates a Snowball program into source code in another language - currently Ada, C, C++, C#, Dart, Go, Java, Javascript, Object Pascal, PHP, Python, Rust and Zig are supported.
The Snowball language and compiler were originally designed and built by Martin Porter. Martin retired from development in 2014 and Snowball is now maintained as a community project. Martin originally named the project as a tribute to SNOBOL, the excellent string handling language from the 1960s. The name Snowball now also serves as a metaphor for how the project grows by gathering contributions over time.
Stemming maps different forms of the same word to a common "stem" - for example, the English stemmer maps connection, connections, connective, connected, and connecting to connect. So a searching for connected would also find documents which only have the other forms.
This stem form is often a word itself, but this is not always the case as this is not a requirement for text search systems, which are the intended field of use. We also aim to conflate words with the same meaning, rather than all words with a common linguistic root (so awe and awful don't have the same stem), and over-stemming is more problematic than under-stemming so we tend not to stem in cases that are hard to resolve. If you want to always reduce words to a root form and/or get a root form which is itself a word then Snowball's stemming algorithms likely aren't the right answer.
Please address all Snowball-related mail to the snowball-discuss mailing list.
Any such mail sent directly to individual developers may be answered less speedily, and in any case they reserve the right to post their answers on snowball-discuss.