Open to two or more interpretations; or of uncertain nature or significance; or (often) intended to mislead. Synonyms: ambiguous; equivocal. Context examples:
Polypropylene, also know as polypropene is a form of plastic just as polyethylene is. What separates polypropylene from polyethylene for starters is the fact that polypropylene can be molded in essence becoming pliable above a certain temperature. When it cools it will return to its solid state.
Hard plastics like polystyrene and poly(methyl methacrylate), are used below their glass transition temperatures; that is in their glassy state. Their Tg's are well above room temperature, both at around 100 o C. Rubber elastomers like polyisoprene and polyisobutylene, are used above their Tg's, that is, in the rubbery state, where they are soft and flexible.