Self-teaching or self-study — learning by oneself (equivalent to 独学). Can be used as a noun (自学) or with する.
大学生の頃は毎日三時間自学していた。
When I was a university student I studied on my own for three hours every day.
忙しくて塾に行けないから、自学で英語を勉強している。
I'm studying English by myself because I'm too busy to go to a cram school.
自学で資格を取る人が増えている。
More people are getting qualifications through self-study.
Regional abbreviation (Hokkaido) for 自動車学校 (driving school) — a local colloquial shortening.
夏休みに自学に通って免許を取ったよ。
I attended a driving school during summer break and got my license.
札幌では自学って言えば自動車学校のことやで。
In Sapporo, if you say 'jigaku' you mean a driving school.