unfrequent

From un- (not) +‎ frequent.

unfrequent (comparative more unfrequent, superlative most unfrequent)

1. Not frequent; not common; not happening often; infrequent.
   • 1827, George Tucker, A Voyage to the Moon‎^[1]:

     He was labouring under a pleurisy, which is not unfrequent in the mountainous region, at this season.

   • 1916, Fedor Jagor, Tomas de Comyn, Chas. Wilkes, Rudolf Virchow., The Former Philippines thru Foreign Eyes‎^[2]:

     It was no unfrequent event, however, for vessels to be lost.

• rare, scarce, uncommon; see also Thesaurus:rare

• unfrequency

From un- (reversive prefix) +‎ frequent.

unfrequent (third-person singular simple present unfrequents, present participle unfrequenting, simple past and past participle unfrequented)

1. (transitive) To stop frequenting; cease to frequent.