Expresses the rarity of an action, event or state; 'hardly', 'rarely', 'seldom'.
Verb-negative + めったにない, い-Adjective-negative + めったにない, な-Adjective-negative + めったにない, Noun-negative + めったにない
Long explanation:
The ~めったにない grammar point is used to express that an action, event or state rarely, hardly, or seldom happens. It is usually combined with a negative verb form. Though it can be used with positive verbs, it is uncommon and sounds unnatural.