Satemisation: PIE *ḱ, *ǵ, *ǵʰ → *ś, *ź, *źʰ (→ CS *s, *z, *z) PIE *kʷ, *gʷ, *gʷʰ → *k, *g, *gʰ Ruki rule: Following *r, *u, *k or *i, PIE *s → *š (→ CS *x) Loss of voiced aspirates: PIE *bʰ, *dʰ, *gʰ → *b, *d, *g Merger of *o and *a: PIE *a/*o, *ā/*ō → PS *a, *ā (→ CS *o, *a) Law of open syllables: All closed syllables (syllables ending in a consonant) are eventually eliminated, in the following stages: Nasalization: With *N indicating either *n or *m not immediately followed by a vowel: PIE *aN, *eN, *iN, *oN, *uN → *ą, *ę, *į, *ǫ, *ų (→ CS *ǫ, *ę, *ę, *ǫ, *y). (NOTE: *ą *ę etc. indicates a nasalized vowel.) In a cluster of obstruent (stop or fricative) + another consonant, the obstruent is deleted unless the cluster can occur word-initially. (occurs later, see below) Monophthongization of diphthongs. (occurs much later, see below) Elimination of liquid diphthongs (e.g. *er, *ol when not followed immediately by a vowel). First palatalization: *k, *g, *x → CS *č, *ž, *š (pronounced , , respectively) before a front vocalic sound (*e, *ē, *i, *ī, *j). Iotation: Consonants are palatalized by an immediately following *j: sj, *zj → CS *š, *ž nj, *lj, *rj → CS *ň, *ľ, *ř (pronounced or similar) tj, *dj → CS *ť, *ď (probably palatal stops, e.g. , but developing in different ways depending on the language) bj, *pj, *mj, *wj → *bľ, *pľ, *mľ, *wľ (the lateral consonant *ľ is mostly lost later on in West Slavic) Vowel fronting: After *j or some other palatal sound, back vowels are fronted (*a, *ā, *u, *ū, *ai, *au → *e, *ē, *i, *ī, *ei, *eu). This leads to hard/soft alternations in noun and adjective declensions. Prothesis: Before a word-initial vowel, *j or *w is usually inserted. Monophthongization: *ai, *au, *ei, *eu, *ū → *ē, *ū, *ī, *jū, *ȳ Second palatalization: *k, *g, *x → CS *c , *dz, *ś before new *ē (from earlier *ai). *ś later splits into *š (West Slavic), *s (East/South Slavic). Progressive palatalization (or "third palatalization"): *k, *g, *x → CS *c, *dz, *ś after *i, *ī in certain circumstances. Vowel quality shifts: All pairs of long/short vowels become differentiated as well by vowel quality: a, *ā → CS *o, *a e, *ē → CS *e, *ě (originally a low-front sound but eventually raised to in most dialects, developing in divergent ways) i, *u → CS *ь, *ъ (also written *ĭ, *ŭ; lax vowels as in the English words pit, put) ī, *ū, *ȳ → CS *i, *u, *y Elimination of liquid diphthongs: Liquid diphthongs (sequences of vowel plus *l or *r, when not immediately followed by a vowel) are changed so that the syllable becomes open: or, *ol, *er, *el → *ro, *lo, *re, *le in West Slavic. or, *ol, *er, *el → *oro, *olo, *ere, *olo in East Slavic. or, *ol, *er, *el → *rā, *lā, *re, *le in South Slavic. Possibly, *ur, *ul, *ir, *il → syllabic *r, *l, *ř, *ľ (then develops in divergent ways). Development of phonemic tone and vowel length (independent of vowel quality): Complex developments (see History of accentual developments in Slavic languages).
Satemisation PIE *ḱ *ǵ *ǵʰ → *ś *ź *źʰ (→ CS *s *z *z) PIE *kʷ *gʷ *gʷʰ → *k *g *gʰ Ruki rule Following *r *u *k or *i PIE *s → *š (→ CS *x) Loss of voiced aspirates PIE *bʰ *dʰ *gʰ → *b *d *g Merger of *o and *a PIE *a/*o *ā/*ō → PS *a *ā (→ CS *o *a) Law of open syllables All closed syllables (syllables ending in a consonant) are eventually eliminated in the following stages Nasalization With *N indicating either *n or *m not immediately followed by a vowel PIE *aN *eN *iN *oN *uN → *ą *ę *į *ǫ *ų (→ CS *ǫ *ę *ę *ǫ *y) (NOTE *ą *ę etc indicates a nasalized vowel) In a cluster of obstruent (stop or fricative) + another consonant the obstruent is deleted unless the cluster can occur word-initially (occurs later see below) Monophthongization of diphthongs (occurs much later see below) Elimination of liquid diphthongs (eg *er *ol when not followed immediately by a vowel) First palatalization *k *g *x → CS *č *ž *š (pronounced   respectively) before a front vocalic sound (*e *ē *i *ī *j) Iotation Consonants are palatalized by an immediately following *j sj *zj → CS *š *ž nj *lj *rj → CS *ň *ľ *ř (pronounced or similar) tj *dj → CS *ť *ď (probably palatal stops eg  but developing in different ways depending on the language) bj *pj *mj *wj → *bľ *pľ *mľ *wľ (the lateral consonant *ľ is mostly lost later on in West Slavic) Vowel fronting After *j or some other palatal sound back vowels are fronted (*a *ā *u *ū *ai *au → *e *ē *i *ī *ei *eu) This leads to hard/soft alternations in noun and adjective declensions Prothesis Before a word-initial vowel *j or *w is usually inserted Monophthongization *ai *au *ei *eu *ū → *ē *ū *ī *jū *ȳ Second palatalization *k *g *x → CS *c  *dz *ś before new *ē (from earlier *ai) *ś later splits into *š (West Slavic) *s (East/South Slavic) Progressive palatalization (or "third palatalization") *k *g *x → CS *c *dz *ś after *i *ī in certain circumstances Vowel quality shifts All pairs of long/short vowels become differentiated as well by vowel quality a *ā → CS *o *a e *ē → CS *e *ě (originally a low-front sound but eventually raised to in most dialects developing in divergent ways) i *u → CS *ь *ъ (also written *ĭ *ŭ; lax vowels as in the English words pit put) ī *ū *ȳ → CS *i *u *y Elimination of liquid diphthongs Liquid diphthongs (sequences of vowel plus *l or *r when not immediately followed by a vowel) are changed so that the syllable becomes open or *ol *er *el → *ro *lo *re *le in West Slavic or *ol *er *el → *oro *olo *ere *olo in East Slavic or *ol *er *el → *rā *lā *re *le in South Slavic Possibly *ur *ul *ir *il → syllabic *r *l *ř *ľ (then develops in divergent ways) Development of phonemic tone and vowel length (independent of vowel quality) Complex developments (see History of accentual developments in Slavic languages)