Self Study
Self Education
noun, verbal noun, の adjective
You are alone in your study. You are studying on your own. This is self study.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
え、全部、独学で勉強したんですか！？
Oh, did you study all of it through self-studying!?
独学の方法なんて、インターネットがあればいくらでも調べられるじゃない。
You can look up any number of self-study methods on the Internet.
独学で学ぶのは効率が悪いんじゃない？
Isn't self-studying inefficient?
インターネットの普及によって、独学で外国語を勉強することは昔よりもずっと簡単になった。
Due to the spread of the Internet, it’s become much easier to learn other languages through self-study nowadays.