Haplology (from Greek ἁπλόος haplóos "simple" and λόγος lógos, "speech") is, in spoken language, the elision (elimination or deletion) of an entire syllable or a part of it through dissimilation (a differentiating shift that affects two neighboring similar sounds). The phenomenon was identified by American philologist Maurice Bloomfield in the 20th century. Linguists sometimes jokingly refer to the phenomenon as "haplogy", an autology. As a general rule, haplology occurs in English adverbs of adjectives ending in "le", for example gentlely → gently; ablely → ably.

The reverse process is known as reduplication, the doubling of phonological material.