What does "anaclastic" mean?

Anaclastic: Springing back, as the bottom of an anaclastic glass. Anaclastic glass, a glass or phial, shaped like an inverted funnel, and with a very thin convex bottom. By sucking out a little air, the bottom springs into a concave form with a smart crack; and by breathing or blowing gently into the orifice, the bottom, with a like noise, springs into its former convex form.