How to say "periodic" in Japanese

• 定期的ていきてきCommon
  na-adjectiveCovers 'periodic' in the sense of occurring at regular intervals, as with periodic maintenance or checkups. It is the natural adjectival choice when describing that something happens regularly.
  彼女かのじょは定期的ていきてきに私をたずねてきたものだった。↗

  She used to visit me regularly.
• 定期ていきJLPT N3approx.Common
  no-adjectiveMatches 'regular; periodic; periodical', but on its own it typically functions as a noun, as in regular passes or periodical publications, rather than as an adjective modifying another word.
  今年ことしも、アマチュア音楽家おんがくかの定期演奏会ていきえんそうかいが頻繁ひんぱんに開催かいさいされる。↗

  This year too there are many regular concerts for amateur musicians being held.

Use 定期的 for the adjectival sense 'happening at regular intervals' (e.g. periodic inspections); 定期 usually works inside compounds or as 'regular/periodical' passes and subscriptions rather than as a free-standing adjective.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 定期的ていきてきperiodic
• ピリオディックperiodic
• 周期的しゅうきてきperiodic
• 定期ていきregular
• 周期性しゅうきせいperiodic