Recurrently antonyms

What is the opposite word for Recurrently?

• rarely

  commonly, frequently
• seldom

  commonly, frequently
• uncommonly

  as a matter of usual practice, commonly
• unusually

  as a matter of usual practice
• infrequently

  commonly, frequently
• not much

  commonly
• never

  every now and then
• erratically

  as a matter of usual practice
• irregularly

  as a matter of usual practice
• unevenly

  as a matter of usual practice