1.
before something happens, in advance, preventive
The state before something (usually something undesirable) has occurred. Almost always used in the phrase 未然に防ぐ (to prevent before it happens). In grammar, refers to the irrealis or imperfective form of a verb.
Usage
未然 is almost always used in the fixed phrase 未然に防ぐ (to prevent before it happens) or 未然に防止する. It is rarely used independently outside this pattern.
In Japanese grammar, 未然形 (irrealis form) is the name of the first verb conjugation base, used before endings like ない (negative) and れる/られる (passive). The term literally means "the form of what has not yet happened."