What is the meaning of the title The Glass Menagerie?

The
title  brings to prominence the collection of figurines composed of
delicate glass and shaped like animals that the equally delicate Laura owns. This title also
helps to draw attention to the symbolism of the fragile glass animals who come to represent
anything that is too delicate to last in the day-to-day outside world.

Because life is harsh and difficult for Laura, she has fabricated an imaginary world
symbolized by the glass menagerie. Laura is even compared to the glass animals in the stage
directions in Scene 6:

She is like a piece of translucent
glass touched by light, given a momentary radiance, not natural, not lasting. 

In a similar fashion, Amanda longs for the world of her youth, in
which she was comfortable as a Southern belle. Tom desires a world that is beyond the mundane
and trivial, escaping in books and at the picture shows (the movies).

Much
like the glass menagerie, all three Wingfields prove to be unrealistic. They each hold another
world in their minds, and, like the glass figures, it is a much too fragile world to last. Thus,
the title of The Glass Menagerie helps to bring to the
front the themes of illusions and impossible dreams.