1.
three years ago; the year before the year before last
More formal equivalent of 三年前. Used in written and formal spoken contexts.
A formal time expression for "three years ago." Follows the pattern of 一昨年 (two years ago) by adding another 昨 prefix. In everyday conversation, 三年前 is far more common.
Related words
Usage
Primarily appears in formal writing such as reports, articles, and official documents. In speech, speakers almost always use 三年前 instead.