infrequent

From in- + frequent.

infrequent (comparative more infrequent, superlative most infrequent)

1. Not frequent; not happening frequently.
   • 1952 October, C. A. Johns, “One Hundred Years at Kings Cross—1”, in Railway Magazine, pages 650-651:

     Such was the station provided for the infrequent services of 1852, when suburban traffic was unheard of, and Hornsey, Colney Hatch & Southgate, Barnet, and Potters Bar were the only intermediate stations on the 17¾ miles between London and Hatfield.

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

• infrequency
• infrequently