a.

1. 接触传染性的
   Chicken pox is a contagious disease.

   水痘是一种通过接触而传染的疾病。

2. （可能）带接触传染原的
3. 照料接触传染病人的
4. （感情等）感染性的；会蔓延的
   Fear can be contagious.

   恐惧会感染他人。

adj.

1. (of a disease) spread by direct or indirect contact of people or organisms.
   ▸having a contagious disease.
2. (of an emotion, attitude, etc.) likely to spread to and affect others:
   her enthusiasm is contagious.