Close-mid back rounded vowel in the context of "Back vowel"

Omega (US: /oʊˈmeɪɡə, -ˈmɛɡə, -ˈmiːɡə/ , UK: /ˈoʊmɪɡə/; uppercase Ω, lowercase ω) is the twenty-fourth and last letter in the Greek alphabet. In the Greek numeric system/isopsephy (gematria), it has a value of 800. The name of the letter was originally ὦ (ō̂ [ɔ̂ː]), but it was later changed to ὦ μέγα (ō̂ méga 'big o') in the Middle Ages to distinguish it from omicron ⟨ο⟩, whose name means 'small o', as both letters had come to be pronounced [o]. In modern Greek, its name has fused into ωμέγα (oméga).

In phonetic terms, the Ancient Greek Ω represented a long open-mid back rounded vowel [ɔː], in contrast to omicron, which represented the close-mid back rounded vowel [o], and the digraph ⟨ου⟩, which represented the long close back rounded vowel [uː]. In modern Greek, both omega and omicron represent the mid back rounded vowel [o̞]. The letter omega is transliterated into a Latin-script alphabet as ō or simply o.

Omicron (US: /ˈoʊmɪkrɒn, ˈɒmɪkrɒn/ , UK: / oʊˈmaɪkrɒn/; uppercase Ο, lowercase ο, Greek: όμικρον) is the fifteenth letter of the Greek alphabet. This letter is derived from the Phoenician letter ayin: . In classical Greek, omicron represented the close-mid back rounded vowel [o] in contrast to omega, which represented the open-mid back rounded vowel [ɔː], and the digraph ⟨ου⟩ which represented the long close back rounded vowel [uː]. In modern Greek, both omicron and omega represent the mid back rounded vowel [o̞]. Letters that arose from omicron include Roman O and Cyrillic O and Ю. The name of the letter was originally οὖ (oû [ûː]), but it was later changed to ὂ μικρόν (ò mikrón 'small o') in the Middle Ages to distinguish the letter from omega ⟨ω⟩, whose name means 'big o', as both letters had come to be pronounced [o]. In modern Greek, its name has fused into όμικρον (ómikron). In the system of Greek numerals, it has a value of 70.

The open-mid back rounded vowel, or low-mid back rounded vowel, is a type of vowel sound, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is ⟨ɔ⟩. The IPA symbol is a turned letter c and both the symbol and the sound are commonly called "open-o". The name open-o represents the sound, in that it is like the sound represented by ⟨o⟩, the close-mid back rounded vowel, except it is more open. It also represents the symbol, which can be remembered as an o which has been "opened" by removing part of the closed circular shape.

In English, the symbol ⟨ɔ⟩ (or ⟨ɔː⟩) is typically associated with the vowel in "thought", but in Received Pronunciation ("RP", standard British English), Australian English, New Zealand English and South African English that vowel is produced with considerably stronger lip rounding and higher tongue position than that of cardinal [ɔ], i.e. as close-mid [oː] or somewhat lower. Open-mid [ɔː] or even open [ɒː] realizations are found in North American English (where this vowel is often indistinguishable from the open back unrounded vowel in "bra") and Scottish English as well as Hiberno-English, Northern England English and Welsh English, though in the last three accent groups closer, [oː]-like realizations are also found. In RP, the open-mid realization of /ɔː/ has been obsolete since the 1930s. Pronouncing that vowel as such is subject to correction for non-native speakers aiming at RP.

Ö, or ö, is a character that represents either a letter from several extended Latin alphabets, or the letter "o" modified with an umlaut or diaeresis. Ö, or ö, is a variant of the letter O. In many languages, the letter "ö", or the "o" modified with an umlaut, is used to denote the close- or open-mid front rounded vowels [ø] or [œ] ; compare the vowel in "girl", which in these languages phonetically could be written: /görl/. In languages without such vowels, the character is known as an "o with diaeresis" and denotes a syllable break, wherein its pronunciation remains an unmodified [o].

Waw (wāw "hook") is the sixth letter of the Semitic abjads, including Phoenician wāw 𐤅, Aramaic waw 𐡅,Hebrew vav ו‎, Syriac waw ܘ and Arabic wāw و‎ (sixth in abjadi order; 27th in modern Arabic order). It is also related to the Ancient North Arabian 𐪅‎‎‎, South Arabian 𐩥, and Ge'ez ወ.

It represents the consonant [w] in classical Hebrew, and [v] in modern Hebrew, as well as the vowels [u] and [o]. In text with niqqud, a dot is added to the left or on top of the letter to indicate, respectively, the two vowel pronunciations.