self-study
US /ˌselfˈstʌd.i/
UK /ˌselfˈstʌd.i/

1.
a method of learning where one learns on their own, without a teacher or formal class
:
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She improved her English through self-study.
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The course is designed for self-study.
1.
to learn or study something on one's own, without a teacher or formal instruction
:
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He decided to self-study for the exam.
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Many online resources allow you to self-study various subjects.