N. infrequency, rareness, rarity, fewness &c. # 103, seldomness, uncommonness

V. be rare

Adj. unfrequent, infrequent, rare, rare as a blue diamond, few, scarce, almost unheard of, unprecedented, which has not occurred within the memory of the oldest inhabitant, not within one's previous experience, not since adam, scarce as hen's teeth, one in a million, few and far between

Adv. seldom, rarely, scarcely, hardly, not often, not much, infrequently, unfrequently, unoften, scarcely, scarcely ever, hardly ever, once in a blue moon, once, once in a blue moon, once in a million years, once for all, once in a way, pro hac vice

Phr. ein mal kein mal