Script

Though all of the language variants could theoretically use either, the scripts differ:

• Bosnian and Montenegrin officially use both the Latin and Cyrillic scripts, but the Latin one is more in widespread use.
• Croatian exclusively uses the Latin alphabet.
• Serbian uses both the Cyrillic and Latin scripts. Cyrillic is the official script of the administration in Serbia and Republika Srpska, but the Latin script is the most widely used in media and especially on the Internet.^{[citation needed]}

Phonemes

Three out of four standard variants have the same set of 30 regular phonemes, so the Bosnian/Croatian/Serbian Latin and Serbian Cyrillic alphabets map one to one with one another and with the phoneme inventory, while Montenegrin alphabet has 32 regular phonemes, the additional two being ⟨Ś⟩ and ⟨Ź⟩.

Some linguists analyse the yat reflexes ⟨je⟩ and ⟨ije⟩, commonly realised as [ie] in Croatian and Bosnian dialects, as a separate phoneme – "jat diphthong" – or even two phonemes, one short and one long. There are even several proposals by Croatian linguists for an orthography reform concerning these two diphthongs, but they have not been seriously considered for implementation.

The standardisation of Montenegrin in 2009 has introduced two new letters, ⟨Ś⟩ and ⟨Ź⟩, for the sounds [ɕ] and [ʑ] respectively. These are optional spellings of the digraphs ⟨sj⟩ and ⟨zj⟩. Critics argue that [ɕ] and [ʑ] are merely allophones of /sj/ and /zj/ in Herzegovinian dialects such as Montenegrin, and therefore the new letters are not required for an adequate orthography.

Most dialects of Serbia and Montenegro originally lack the phoneme /x/, instead having /j/, /v/, or nothing (silence). /x/ was introduced with language unification, and the Serbian and Montenegrin standards allow for some doublets such as snaja–snaha and hajde–ajde. However, in other words, especially those of foreign origin, ⟨h⟩ is mandatory.

In some regions of Croatia and Bosnia, the sounds for letters ⟨č⟩ (realised as [tʂ] in most other dialects) and ⟨ć⟩ [tɕ] merged or nearly merged, usually into [tʃ]. The same happened with their voiced counterparts, i.e. ⟨dž⟩ ([dʐ]) and ⟨đ⟩ ([dʑ]) merged into [dʒ]. As result, speakers of those dialects often have difficulties distinguishing these sounds.

Orthography

The Serbian variety usually phonetically transcribes foreign names and words (although both transcription and transliteration are allowed), whereas the Croatian standard usually transliterates. Bosnian and Montenegrin accept both models, but transliteration is often preferred.

Also, when the subject of the future tense is omitted, producing a reversal of the infinitive and auxiliary "ću", only the final "i" of the infinitive is orthographically elided in Croatian and Bosnian, whereas in Serbian and Montenegrin the two have merged into a single word:

• "Uradit ću to." (Croatian/Bosnian)
• "Uradiću to." (Serbian/Montenegrin)

Accentuation

In general, the Shtokavian dialects that represent the foundation of the four standard varieties have four pitch accents on stressed syllables: falling tone on a short vowel, written e.g. ⟨ı̏⟩ in dictionaries; rising tone on a short vowel, written e.g. ⟨ì⟩; falling tone on a long vowel, written e.g. ⟨î⟩; and rising tone on a long vowel, written e.g. ⟨í⟩. In addition, the following unstressed vowel may be either short, ⟨i⟩, or long, ⟨ī⟩. In declension and verb conjugation, accent shifts, both by type and position, are very frequent.

The distinction between four accents and preservation of post accent lengths is common in vernaculars of western Montenegro, Bosnia and Herzegovina, in parts of Serbia, as well as in parts of Croatia with a strong Serb presence. In addition, a distinct characteristics of some vernaculars is stress shift to proclitics, e.g. phrase u Bosni (in Bosnia) will be pronounced /ǔ bosni/ instead of /u bôsni/ as in northern parts of Serbia.

The northern vernaculars in Serbia also preserve the four-accent system, but the unstressed lengths have been shortened or disappeared in some positions. However, the shortening of post-accent lengths is in progress in all Shtokavian vernaculars, even in those most conservative in Montenegro. Stress shift to enclitics is, however, in northern Serbia rare and mostly limited to negative verb constructs (ne znam = I don't know > /nê znaːm/).

The situation in Croatia, is however, different. A large proportion of speakers of Croatian, especially those coming from Zagreb, do not distinguish between rising and falling accents.^[24][25] This is considered to be a feature of the Zagreb dialect, which has strong Kajkavian influence, rather than standard Croatian.^[25]

Regardless of vernacular differences, all three standard varieties exclusively promote the Neo-Shtokavian four-accentual system. Both dialects that are considered to be the basis of standard Serbian (Eastern Herzegovinian and Šumadija-Vojvodina dialects) have four accents.

Phonetics

Morphology

There are three principal "pronunciations" (izgovori/изговори) of the Shtokavian dialect that differ in their reflexes of the Proto-Slavic vowel jat. Illustrated by the Common Slavic word for "child", dětę, they are:

• dite in the Ikavian pronunciation
• dijete in the Ijekavian pronunciation
• dete in the Ekavian pronunciation

The Serbian language recognises Ekavian and Ijekavian as equally valid pronunciations, whereas Croatian, Montenegrin and Bosnian accept only the Ijekavian pronunciation. In Bosnia and Herzegovina (regardless of the official language) and in Montenegro, the Ijekavian pronunciation is used almost exclusively.

Ikavian pronunciation is nonstandard, and is limited to dialectal use in Dalmatia, Lika, Istria, central Bosnia (area between Vrbas and Bosna), Western Herzegovina, Bosanska Krajina, Slavonia and northern Bačka (Vojvodina). So, for example:

A few Croatian linguists have tried to explain the following differences in morphological structure for some words, with the introduction of a new vowel, "jat diphthong". This is not the opinion of most linguists.

Sometimes this leads to confusion: Serbian and Montenegrin poticati (to stem from) is in Croatian and Bosnian "to encourage". Croatian and Bosnian "to stem from" is potjecati, whereas Serbian and Montenegrin for "encourage" is podsticati.

Standard Bosnian allows both variants, and ambiguities are resolved by preferring the Croatian variant; this is a general practice for Serbian–Croatian ambiguities.

The phoneme /x/ (written as h) has been volatile in eastern South Slavic dialects. In Serbian, Montenegrin and some Croatian dialects (including some of those in Slavonia), it has been replaced with /j/, /v/, or elided, and subsequent standardisation sanctioned those forms:

However, /x/ and /f/ have been kept in many words as a distinct feature of Bosnian speech and language tradition, particularly under influence of Turkish and Arabic, and even introduced in some places where it etymologically did not exist. Those forms were in the mid 1990s also accepted in the orthography of the Bosnian language.^[30][31] However, 2018, in the new issue of the Orthography of the Bosnian language, words without the phoneme /x/ (written as "h") are accepted due to their prevalence in language practice.^[32]

Because the Ijekavian pronunciation is common to all official standards, it will be used for examples on this page. Other than this, examples of different morphology are:

Internationalisms

Also many internationalisms and transliterations are different:

(cf. German organisieren, konstruieren, analysieren)

Historically, modern-age internationalisms entered Bosnian and Croatian mostly through German and Italian, Montenegrin mostly through Italian, whereas they entered Serbian through French and Russian, so different localisation patterns were established based on those languages. Also, Greek borrowings came to Serbian directly, but through Latin into Croatian:

Most of terms for chemical elements are different: for international names, Bosnian and Croatian use -ij where Serbian and Montenegrin have -ijum (uranij–uranijum). In some native names, Croatian has -ik where Serbian and Montenegrin have -(o)nik (kisik–kiseonik "oxygen", vodik–vodonik "hydrogen"), and Bosnian accepts all variants. Yet others are totally different (dušik–azot 'nitrogen', kositar–kalaj 'tin'). Some element names are the same: srebro (silver), zlato (gold), bakar (copper).

Some other imported words differ by grammatical gender, feminine words having an -a suffix and masculine words having a zero-suffix:

Pronouns

In Serbian, Montenegrin and Bosnian, the pronoun what is što when used as a relative, but šta when used as an interrogative; the latter applies also to relative sentences with interrogative meaning. Croatian uses što in all contexts (but in colloquial speech, "šta" is often used).

This is applicable only to the nominative and the accusative – in all other cases, the standards have the same forms: čega, čemu etc. for što.

In Croatian, the pronoun who has the form tko, whereas in Serbian, Bosnian and Montenegrin it has ko, but again, in colloquial speech, the initial "t" is usually omitted. The declension is the same: kome, koga, etc. In addition, Croatian uses komu as an alternative form in the dative case.

The locative pronoun kamo is only used in Croatian:

Syntax

Examples

The greatest differences between the standards is in vocabulary. However, most words are well understood, and even occasionally used, in the other standards. In most cases, common usage favours one variant and the other(s) are regarded as "imported", archaic, dialectal, or simply more rarely used.

Note that there are only a few differences that can cause confusion, for example the verb "ličiti" means "to look like" in Serbian, Montenegrin and Bosnian, but in Croatian it is "sličiti"; "ličiti" means "to paint (a house)". However, "ličiti" is often used Croatian in the meaning of "to look like".

The word "bilo" means "white" in the Ikavian accent, "pulse" in official Croatian, and "was" in all official languages, although it is not so confusing when pronounced because of different accentuation (bîlo or bílo = white, bı̏lo = pulse, bílo = was).

In Serbian, Montenegrin and Bosnian, the word izvanredan (extraordinary) has only the positive meaning (excellent), vanredan being used for "unusual" or "out of order"; however, only izvanredan is used in Croatian in both contexts.

Also note that in most cases Bosnian officially allows almost all of the listed variants in the name of "language richness", and ambiguities are resolved by preferring the Croatian variant. Bosnian vocabulary writers based their decisions on usage of certain words in literary works by Bosnian authors.