One who or that which repeats.

(education) A student repeating a course or class.

(medicine) A patient who repeatedly presents with the same symptoms.

(marketing) A consumer who repeatedly purchases the same goods or services.

(US) One who votes more than once at an election.

(ufology) A person who regularly sees unexplained sightings of paranormal phenomena.

A telegraphic instrument for automatically retransmitting a message.

(electronics) An electronic device that receives a weak or low-level signal and retransmits it at a higher level or higher power.

(horology) A watch with a striking apparatus which, upon pressure of a spring, will indicate the time, usually in hours and quarters.

(nautical) A frigate appointed to attend an admiral in a fleet, and to repeat the admiral's signals.

(nautical) A pennant used to indicate that a certain flag in a hoist of signal is duplicated.

(mathematics) A repeating decimal.

(textiles) In calico printing, a design repeated at equal intervals in a pattern.