crown glass

English Thesaurus

1. optical glass of low dispersion and low refractive index (noun.substance)

hypernym	:	optical glass,
definition	:	clear homogeneous glass of known refractive index; used to make lenses (noun.substance)

2. a glass blown into a globe which is later flattened and spun to form a disk (noun.substance)

hypernym	:	glass,
definition	:	a brittle transparent solid with irregular atomic structure (noun.substance)