Antonyms of adj fortnightly

1 sense of fortnightly

Sense 1
fortnightly, biweekly -- (occurring every two weeks)

INDIRECT (VIA periodic) -> aperiodic, nonperiodic -- (not recurring at regular intervals)

Similarity of adj fortnightly

1 sense of fortnightly

Sense 1
fortnightly, biweekly -- (occurring every two weeks)
       => periodic (vs. aperiodic), periodical -- (happening or recurring at regular intervals; "the periodic appearance of the seventeen-year locust")

Synonyms of adv fortnightly

1 sense of fortnightly

Sense 1
fortnightly, biweekly -- (every two weeks; "he visited his cousins fortnightly")