ATTENUATE
Meaning of ATTENUATE in English
at ‧ ten ‧ u ‧ ate /əˈtenjueɪt/ BrE AmE verb [transitive]
formal to make something weaker or less:
an attenuated form of the polio virus
Longman Dictionary of Contemporary English.
Longman - Словарь современного английского языка.
2012