Axiom is  a general purpose Computer Algebra system. It is useful for research and development of mathematical algorithms. It defines a strongly typed, mathematically correct type hierarchy. It has a programming language and a built-in compiler.
Polybutylene is simply a type of plumbing material that was manufactured between the late 70's and early 90's. It is thought that it was installed in over 6 million homes during that time period.
Participatory budgeting (PB) is a process of democratic deliberation and decision-making, and a type of participatory democracy, in which ordinary people decide how to allocate part of a municipal or public budget.