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This page might be incomplete — you are advised to refer to the article Loglan on the lojban.org wiki.

Loglan (loglang)
La Loglan
created in: 1955
by: James Cooke Browne
influenced by:none (first of its kind)

Loglan ([ˈlɒg.læn]; natively [ˈloglan] ‘logical language’) is the earliest recognized example of a logical language, created by James Cooke Brown in 1955. Its subsequent development and promotion was led by The Loglan Institute (TLI).







Loglan Institute v. Logical Language Group



The Loglan alphabet
IPA a b ʃ d ɛ f ɡ h i, j ʒ k l, l̩ m, m̩ n, n̩ o p θ r s t u, w v y x ə z ˈ ʔ .
Latin a b c d e f g h i j k l m n o p q r s t u v w x y z ' . ,

The letters ⟨q⟩, ⟨w⟩ and ⟨x⟩ are restricted to names, as they represent 'nonnative' sounds.

Loglan makes use of several conventions for distinguishing syllabic and nonsyllabic variants of close vowels and sonorant consonants. Consonants may be doubled to indicate syllabicity, or may be left single in cases where that would not cause ambiguity, as in ⟨brt⟩ 'Bert'. The letters ⟨i⟩ and ⟨u⟩ represent nonsyllabic glide sounds when they occur before other vowel letters. ⟨i⟩ behaves similarly in the pairs ⟨ai⟩, ⟨ei⟩ and ⟨oi⟩, which represent falling diphthongs. The letter ⟨o⟩ is nonsyllabic in the digraph ⟨ao⟩, which represents a diphthong similar to that found in the name 'Mao Zedong' in English and Pinyin orthography.


Loglan has six vowels and 17 consonants for native words, according to the analysis found in Loglan I[1]. In addition, there are several marginal phonemes that have orthographic representation. If these, plus syllabic consonants and non-syllabic vowels (i.e. semivowels), are counted, Loglan has a total of seven vowels and 26 consonants. Loglan phonology is notable for its high prevalence of consonant clusters, including many clusters that are cross-linguistically uncommon, as a result of its morphology and word-generation procedure. Loglan has phonemic stress.


Loglan vowel phonemes
Front Central Back
Close i (y) u
Mid ɛ ə o
Open a

/ɛ/ is realized as /eɪ̯/ before vowels. This may be a particular case of glide insertion, which is optional to break up vowel clusters.

Diphthongs and semivowels

Loglan has four falling diphthongs: /aɪ̯/, /aʊ̯/~/ao̯/, /eɪ̯/ and /oɪ̯/. The diphthong /aʊ̯/~/ao̯/ is spelled ⟨ao⟩. When the high vowels, /i/ and /u/, precede any vowel, they become nonsyllabic in standard Loglan, resulting in sequences that may be analyzed as [semivowel]+[vowel] or as rising diphthongs. That is, /ia/, /iɛ/, /ii/, /io/, /iu/, /ua/, /uɛ/, /ui/, /uo/ and /uu/ are realized as [ja] [jɛ], [ji], [jo], [ju], [wa], [wɛ], [wi], [wo] and [wu]. However, disyllabic pronunciations of these sequences are also permitted, with stress going on the first vowel. In names, syllabicity is fully contrastive; hiatus may be indicated in writing with ⟨,⟩.<ref>. Although — names aside — Loglan can be described without semivowels, this article will include them in Loglan's inventory as marginal phonemes, and utilize /j/ and /w/ in transcriptions.


Loglan consonant phonemes
labial interdental dental or alveolar palatal velar glottal
plosive p b t d k g (ʔ)
fricative f v (θ) s z ʃ ʒ (x) h
nasal m (m̩) n (n̩)
lateral l (l̩)
rhotic r (r̩)
semivowel (w) (j)

The glottal stop is the most common realization of a "pause" phoneme which occurs with high frequency between vowels and at word boundaries. Syllabic consonants are contrastive in names, although [[Loglan I] describes them as "allophones."





Word shapes

Word classes



Place structures



Other features

Unresolved issues



Semantic and philosophical


Academic reception





  1. | url = http://loglan.org/Loglan1/chap2.html#sec2.3 | title = 2.3 The Size of the System | work = Loglan 1 | publisher = The Loglan Institute | accessdate = 30 April 2020 | ref = none