1. having a strong physical reaction to an external or internal stimulus;
2. the ability to record small changes in weight, temperature, etc.;
3. an ability to understand what other people need; be helpful and kind to them;
4. the fact of a situation, subject, etc. needing to be dealt with carefully;
5. the tendency to become upset about things;
6. the quality of being easily influenced, changed, or damaged;
7. the quality of needing to be treated with care or secrecy.
   

The word “sensitivity” first appeared in English in the 14th century, originally used in the medical sense of the ability to sense or respond to stimuli.
Over time, the word gradually expanded in meaning to include emotional and psychological sensitivity, as well as the vulnerability associated with such sensitivity.

Learn more here Meanings of Sense And Sensitivity or Why Sense and Sensitivity.

You may also lilke to check out the definition of Sense