1
: knowledge and skill that allows you to do, use, or understand something very well : command
—usually + of
We were impressed by her mastery of the subject.
She achieved a complete mastery of French.
2
: complete control of something
He struggled to gain mastery of/over his fears.
Cite this Entry
“Mastery.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/mastery. Accessed 16 Apr. 2026.
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