to become a master of something or to achieve complete mastery or control over something.
From 'be-' plus 'master'. This verb means to make oneself master of something or to master it completely.
You can see in 'bemaster' why the 'be-' prefix eventually fell away—'master' could already be a verb, so adding 'be-' felt redundant, teaching us why language naturally sheds the words it doesn't really need.
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