Haplography (from Greek: haplo- 'single' + -graphy 'writing'), also known as lipography, is a scribal or typographical error where a letter or group of letters that should be written twice is written once. It is not to be confused with haplology, where a phoneme is omitted to prevent two similar sounds from occurring consecutively: the former is a textual error, while the latter is a phonological process. In English, a common haplographical mistake is the rendering of consecutive letters between morphemes as a single letter. Many commonly misspelled words have this form. For example, misspell is often misspelled as. The etymology of the word misspell is the affix "mis-" plus the root "spell", their bound morpheme has two consecutive ss, one of which is often erroneously omitted. The reverse phenomenon, in which a copyist inadvertently repeats a portion of text, is known as dittography. Other examples of words liable to be written haplographically in different languages are: German Rollladen ("shutters", from roll + Laden) which requires an uncommon sequence of three l‘s and is often spelt, or Arabic takyīf تكييف ("air conditioning"), which would require a sequence of two semivowels y (one as a true semivowel, and another as a device to mark long ī) and is often misspelt as takīf , with only one. The term haplography is commonly used in the field of textual criticism to refer to the phenomenon of a scribe's, copyist's or translator's inadvertently skipping from one word or phrase to a similar word or phrase further on in the text, and omitting everything in between. It is considered to be a form of parablepsis.