Roget's Thesaurus of English Words and Phrases by Peter Mark Roget

seldomness†; uncommonness. V. be rare &c adj.. Adj. unfrequent†, infrequent; rare, rare as a blue diamond; few &c 103; 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 [Lat.]. Phr. ein mal kein mal [G.].