1. Pertaining to a period; performed by revolution in a certain time; happening or appearing regularly at a stated time after a fixed interval; constituting a complete sentence; pertaining to or in the manner of a periodical.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• perioid,
• periodoc,
• periadic,
• periodly,
• pariotic,
• periodm,
• periotic,
• periodics,
• periodin,
• nerodic,
• periodicle,
• perodic,
• peridic,
• perioda,
• preiodic,
• peridiodic,
• peroidic,
• periodds,
• peirodic,
• periodicly

• periodical,
• periodicity,
• perdicidae,
• perdicinae.

The adjective form of the word "periodic" is "periodical".

The plural form of the word "periodic" is "periodics".

The singular form of the word "periodic" is "period"