型 (xíng) is a bound morpheme (bound form) that cannot stand alone as a word. It attaches to other morphemes to form common nouns meaning 'type, model, pattern' — you'll see it in 模型 (model), 类型 (type), 典型 (typical), and 新型 (new type). It can also refer to a concrete 'mold' for casting, as in 模型 (mold) or 铸型 (casting mold). Because it's a suffix, you always use it as part of a compound; never treat it as an independent noun.