Reduplication

In morphology, reduplication is an operation which copies some part (or all) of the base and attaches the copied element (the reduplicant) to the base. The copied element that is attached to the base is called reduplicant. Reduplication is a kind of non-linear morphology.

Reduplication is a word formation process by which some part of a base (= a segment, syllable, morpheme) is repeated, either to the left, or to the right, or, occasionally, in the middle.

Reduplication forms a predictable grammatical pattern, it is not any kind of repetition of phonological material. The function can be semantic (intensity, plurality, etc) or grammatical (agreement with subject, aspect, etc).

Examples
Ponapean duhp 'dive', du-duhp 'be diving' (reduplication of a CV syllable, Rehg 1981:78).

Tagalog has many reduplication rules, resulting in forms like (i) and (ii):

(i) sulat			'writing' su-sulat  		'will write' (ii) mag-sulat-sulat	       'to write intermittently'

Subtypes

 * partial reduplication
 * full reduplication
 * prereduplication
 * postreduplication

Origin
The use of this term in its modern sense goes back at least to the 18th century.

Links
Utrecht Lexicon of Linguistics

Other languages
German Reduplikation