What is rigid?

Famous quotes containing the word rigid:

    Let’s call something a rigid designator if in every possible world it designates the same object, a non-rigid or accidental designator if that is not the case. Of course we don’t require that the objects exist in all possible worlds.... When we think of a property as essential to an object we usually mean that it is true of that object in any case where it would have existed. A rigid designator of a necessary existent can be called strongly rigid.
    Saul Kripke (b. 1940)

    I found a dimpled spider, fat and white,
    On a white heal-all, holding up a moth
    Like a white piece of rigid satin cloth—
    Assorted characters of death and blight
    Robert Frost (1874–1963)

    The loosening, for some people, of rigid role definitions for men and women has shown that dads can be great at calming babies—if they take the time and make the effort to learn how. It’s that time and effort that not only teaches the dad how to calm the babies, but also turns him into a parent, just as the time and effort the mother puts into the babies turns her into a parent.
    Pamela Patrick Novotny (20th century)