Rare, literary, or technical term for glass; in everyday language, ガラス is used instead. The kanji 硝子 are ateji and not commonly encountered.
See also: ガラス
In old documents, 硝子 is sometimes used to write しょうし, meaning glass.
In modern times, ガラス is more common than 硝子.
hyaline cartilage
A Sino-Japanese term written 硝子 and read with the regular on-readings しょう and し; the characters are not phonetic ateji.