The milkiness of this glass of milk makes me wonder if it's still drinkable.

milkiness 是由名词 milk（牛奶）加上后缀 -ness 构成的名词。-ness 是常见的名词后缀，表示某种性质或状态。milkiness 的字面意思是"牛奶的性质"，在这里特指"牛奶的浑浊度"。