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.
Hyponyms (each of the following is a kind of Pb): hard lead (unrefined lead that is hard because of the impurities it contains). antimonial lead; hard lead (a lead alloy that contains about 5% antimony). pig lead (lead that is cast in pigs). PB (noun). The noun PB has 1 sense: 1. a soft heavy toxic malleable metallic element; bluish white when freshly cut but tarnishes readily to dull grey. Familiarity information: PB used as a noun is very rare.