Not occurring often; rarely.

कभी-कभार

English Usage: She visits her relatives infrequently.

Hindi Usage: वह अपने रिश्तेदारों से कभी-कभार मिलती है।

Occurring only at long intervals; not frequent.

असामान्य

English Usage: The infrequent rains caused concern among the farmers.

Hindi Usage: असामान्य बारिशों ने किसानों में चिंता पैदा की।