susceptible

adj

1. Likely to be affected by something.

   “He was susceptible to minor ailments.”

2. Easily influenced or tricked; credulous.
3. Especially sensitive, particularly to a stimulus.
4. That, when subjected to a specific operation, will yield a specific result.

   “Rational numbers are susceptible of description as quotients of two integers.”

   “A properly prepared surface is susceptible of an enduring paint job.”

5. Vulnerable.

   “The visitors were being pinned back by the end of the first half. Yet Gordon Strachan's side played with great conviction and always had a chance of springing a surprise when their opponents were so susceptible at the back.”

6. Amenable.

   “In the next several chapters, we put the basic tools to work in different contexts with particular specification of return and transition equations designed to render the Bellman equation susceptible to further analysis and computation.”

noun

1. A person who is vulnerable to being infected by a certain disease

   “In either instance a decrease in the number of susceptibles, by making the spread of virus less easy, tends towards a stage at which the infection dies out.”