1 (wiktionary) 2 (es.wikipedia) 3 (en.wikipedia) 4 (glosbe)

Verbs Nouns Adjectives/Adverbs Pronouns Prepositions Conjunctions
selten (Advanced search)

infrequent {adj} (Not frequent; not happening frequently) it never rains but it pours {proverb} (unfortunate events occur in quantity) misfortunes never come singly {proverb} (proverb) rare {adj} (very uncommon) rare earth {n} (naturally occurring oxides of the lanthanide metals) rare earth element {n} (type of metal) rarely {adv} (not occurring at a regular interval) rarity {n} (measure of the scarcity of an object) rarity {n} (rare object) seldom {adv} (infrequently, rarely) when it rains, it pours {proverb} (if a person encounters bad luck, more bad luck will follow)

Hardly ever have we seen such a night !	¡Casi nunca hemos visto una noche así!
How did you come by those rare books ?	¿Cómo conseguiste esos libros raros?
Seldom do I see him .	Pocas veces lo veo.
She is seldom late for school .	Rara vez llega tarde a la escuela.
We took turns with the driving .	Nos turnamos con la conducción.
Father seldom comes home before eight .	El padre rara vez llega a casa antes de las ocho.
They mistook him for his brother .	Lo confundieron con su hermano.
She rarely , if ever , goes out of town .	Rara vez, o nunca, sale de la ciudad.
It is rare for him to get angry .	Es raro que se enfade.
He writes to me less and less often these days .	Me escribe cada vez menos en estos días.
He seldom , if ever , goes to the movies .	Rara vez, o nunca, va al cine.
She seldom goes out .	Ella rara vez sale.
He is not seldom ill .	No es raro que esté enfermo.