Japanese syntax also has remained relatively stable, maintaining its characteristic subject–object–verb (SOV) sentence structure. A notable change in that domain is the obliteration of the distinction between the conclusive form—the finite form that concludes a sentence—and the noun-modifying form exhibited by certain predicates. For example, in early Japanese otsu and tsuyoshi were conclusive forms, respectively, of the verb ‘to drop’ and the adjective ‘to be strong.’ When these words were used as noun modifiers, the forms were inflected as otsuru, tsuyoki. The distinction between conclusive forms and noun-modifying forms played an important role in the phenomenon of syntactic concord that, for example, called for the noun-modifying forms of predicate even in concluding the predication when a subject or some other word was marked by particles such as the emphatic zo or the interrogative ka or ya. That system of syntactic concord deteriorated in Middle Japanese, and the distinction between the conclusive forms and the noun-modifying forms was also lost, the latter dominating the former. Such modern forms as ochiru ‘to drop’ and tsuyoi ‘to be strong’ are the descendants of the earlier noun-modifying forms.

A single most important development in the history of Japanese is the acquisition of the nativized writing systems that took place between the 8th and the 10th centuries. The Japanese vocabulary has been constantly enriched by loanwords—from Chinese in earlier times and from European languages in more recent history.

The word-pitch accent system

Both moras and syllables play an important role in the Japanese accentual system, which can be characterized as a word-pitch accent system, in which each word (as contrasted with each syllable as in the prototypical tone languages of Southeast Asia) is associated with a distinct tone pattern. In Tokyo, for example, hashi with a high-low (HL) tone denotes ‘chopstick,’ but with a low-high (LH) tone it denotes ‘bridge’ or ‘edge, end.’ In Kyōto, on the other hand, hashi with a high-low tone means ‘bridge,’ and with a low-high tone it means ‘chopstick,’ whereas the word for ‘edge, end’ is pronounced with a flat high-high tone. The accentual system is one of the features that distinguishes one dialect from another, as each dialect has its own system, though certain dialects in the Tohoku region of northeastern Honshu and in Kyushu and some other areas show no pitch contrast.

In the majority of dialects, the pitch change occurs at the mora, not the syllable, boundary. The Tokyo form kan is a monosyllabic word, but, because it is dimoraic, pitch may change from high to low at the mora boundary, yielding kan (spoken with a high-low tone), which means ‘official,’ or (spoken with a low-high tone) ‘sense.’ Syllables, however, are units that determine the number of potential accentual distinctions, so that, given the possibility of unaccented forms, one-syllable words make two potential distinctions, two-syllable words three potential distinctions, and so forth. Thus, a monosyllabic word such as e can be either accented or unaccented and can be realized as a high-tone word (if accented) or as a low-tone word (if unaccented). The distinction, however, can be observed only when the form in question is followed by a particle such as the nominative particle ga; e-ga (LH) means ‘handle [nominative]’ and e-ga (HL) ‘picture [nominative].’ Since the number of potential distinctions is determined by the number of syllables in a word, monosyllabic and dimoraic words make only two potential distinctions. Thus, while there are accented kan-ga (high-low–low) ‘official [nominative]’ and unaccented kan-ga (low-high–high) ‘sense [nominative],’ there is no word pronounced with a low-high–low pitch. In other words, in the Tokyo dialect the number of potential accentual contrasts equals the number of syllables plus one. The absence of stress accent of the English type, the sequences of high-pitched moras as well as those of low-pitched moras, rather than alternating stressed and unstressed syllables, and the mora-timed characteristic together render Japanese speech rather monotonous compared to a stress-accent language like English or a true tone language like Chinese.

Phonemes

Japanese has the following phonemes: 5 vowels /i, e, a, o, u/, 16 consonants /p, t, k, b, d, g, s, h, z, r, m, n, w, j, N, Q/. The high back vowel u is unrounded [ɯ]. That and the other high vowel i tend to be devoiced between voiceless consonants or in final position after a voiceless consonant. The most pervasive phonological phenomena are palatalization and affrication, which turn t, s, d/z, and h into [tʃ], [ʃ], [dƷ], and [ç] before i, respectively, and t and d/z into [ts] and [dz] before u, respectively. The phoneme h also changes to [ɸ] before u. The effects of these processes are seen in inflected forms of verbs as well as in foreign loans—e.g., /kat-e/ ‘win [imperative]’ /kat-anai/ ‘win [negative],’ /kat-oo/ ‘win [cohortative],’ /katʃ-imasɯ/ ‘win [polite],’ /kats-ɯ/ ‘win [present]’; the English word tool becomes /tsɯɯrɯ/, ticket becomes /tʃiketto/, and single becomes /ʃiŋgɯrɯ/.