noun
tolerability
Primarily a medical/pharmacological term referring to the degree to which a drug or treatment can be tolerated by a patient without unacceptable adverse effects.
新薬の忍容性を評価する臨床試験が行われた。
A clinical trial was conducted to evaluate the tolerability of the new drug.
安全性 means safety in a broader sense, whereas 忍容性 specifically focuses on the acceptability of side effects.
Compound of 忍容 (にんよう, 'tolerance, acceptance') + 性 (せい, '-ity, -ness'). The exact historical derivation is uncertain, but the term is used in modern medical Japanese.