Haplology

Haplology is the reduction of a sequence of two identical or very similar syllables to a single such syllable.

Examples

 * Middle English humblely > Modern English humbly (Campbell 1998:37)
 * Basque sagar "apple" + ardo "wine" > sagardo "cider" (Trask 1996:68)

Example
the English possessive 's is not pronounced after the plural morpheme -s (e.g. John's reaction vs. the two cats' reactions). In Dutch, the noun-forming suffix -eling may attach to nouns, verbs and adjectives (dorpeling 'villager', zuigeling 'infant', stommeling 'idiot'). If the base ends in the sequence -el, one of the -el-sequences is haplologically deleted (edel 'noble', edeling 'nobleman').

Link
Utrecht Lexicon of Linguistics

Other languages

 * French haplologie (fr)
 * German Haplologie (de)
 * Russian гаплология