Found:

reduplication

PHONOLOGY/MORPHOLOGY: 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. EXAMPLE: Tagalog, a language spoken at the Philippines 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'