reflectivity; reflectiveness
Physics term for the property of a surface to reflect light or other radiation.
This material has high reflectivity, so it reflects light well.
reflexivity; reflexiveness
Physiology term for the property of being reflexive, i.e., involving an involuntary response.
The patellar tendon reflex is an example of reflexivity.
reflex syncope
Compound of 反射 (reflection/reflex) + 性 (property/nature). The exact historical derivation is uncertain, but the word follows a common pattern for forming abstract nouns from technical terms.