3. RECURRENT TIME
[Nouns] infrequency, rareness, rarity; fewness [more]; seldomness; uncommonness.
[Adjectives] unfrequent, infrequent; rare, rare as a blue diamond; few [more]; scarce; almost unheard of, unprecedented, which has not occurred within the memory of the oldest inhabitant, not within one's previous experience.
once; once for all, in a way; pro hac vice.