What does "hypersensitive" mean?

Highly or abnormally sensitive to some substances or agents, especially to some allergen.

Hypersensitive

Common synonyms include: allergic, allergic, allergic reaction, anaphylactic, delicate, empathetic.

adj

adj ·5 syllables ·Uncommon ·College level

Adjective

1
Highly or abnormally sensitive to some substances or agents, especially to some allergen.
2
Excessively sensitive; easily offended.

Adjective

1
having an allergy or peculiar or excessive susceptibility (especially to a specific factor) wordnet

"A dog's sense of hearing is hypersensitive."

From hyper- + sensitive. Doublet of supersensitive.