contagious

infectious, contagious

这一对词都是形容词，又都具有“传染性的”、“传染病的”意义，但内涵和使用场合有所不同。
infectious: infectious修饰的是“间接传染的病”，指病菌通过空气、食物、水、衣服、容器等物的传染。

• tuberculosis is an infectious disease.
  肺结核是一种传染病。
• it's said that cancer is not infectious.
  据说癌症是不会传染的。

contagious: contagious修饰的是“直接传染的病”，一般指跟病人直接接触而感染的病。

• scarlet fever is a contagious disease.
  猩红热是一种传染病。
• measles and aids are highly contagious.
  麻疹和艾滋病是很易传染的。

形容词 contagious:

1. easily diffused or spread as from one person to another
2. (of disease) capable of being transmitted by infection
   同义词：catching, communicable, contractable, transmissible, transmittable

1. A period of time during which a vehicle, person, or material suspected of carrying a contagious disease is detained at a port of entry under enforced isolation to prevent disease from entering a country.
   检疫期，隔离期当运输工具、人或材料被怀疑带有传染性疾病，被扣留在港口进行强行隔离的一段期限，以防止疾病传入某个国家
2. An acute contagious viral infection characterized by inflammation of the respiratory tract and by fever, chills, muscular pain, and prostration.
   流行性感冒一种急性的有传染性的病毒感染，主要特征是呼吸道感染和发烧、寒战、肌肉疼痛和虚脱
3. Scarlet fever is highly contagious.
   猩红热传染性很强。
4. He has contagious laughter.
   他有着容易感染人的笑声。