Defective script

A defective script is a writing system that does not represent all the phonemic distinctions of a language. For example, Italian has seven vowels, but the Italian alphabet has only five vowel letters to represent them; in general, the differences between /e, ɛ/ and /o, ɔ/ are simply ignored, though when stress marks are used they may distinguish them. Among the consonants, both /s/ and /z/ are written ⟨s⟩, and both /ts/ and /dz/ are written ⟨z⟩, though not many words are distinguished by the latter. Stress and hiatus are not reliably distinguished.

Such imperfections are nothing new. The Greek alphabet was defective during its early history. Classical Greek had distinctive vowel length: five short vowels, /i e a o u/, and seven long vowels, /iː eː ɛː aː ɔː oː uː/. When the Phoenician alphabet was adapted to Greek, the names of five letters were pronounced by the Greeks with initial consonants made silent, and were then used acrophonically to represent vowels. These were alpha, e (later called e psilon), iota, o (later called o micron), and u (later called u psilon) – α, ε, ι, ο, υ – five letters for twelve vowel sounds. Later the [h] dropped from the Eastern Greek dialects, and the letter heta (now pronounced eta) became available; it was used for /ɛː/. About the same time the Greeks created an additional letter, omega, probably by writing omicron with an underline, that was used for /ɔː/. Digraphs ei and ou were devised for /eː/ and /oː/. Thus Greek entered its classical era with seven letters and two digraphs – α, ε, ι, ο, υ, η, ω, ει, ου – for twelve vowel sounds. Long /iː aː uː/ were never distinguished from short /i a u/, even though the distinction was meaningful. Although the Greek alphabet was a good match to the consonants of the language, it was defective when it came to some vowels.

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