Ivšić's law is a Common Slavic accent law named after Croatian accentologist Stjepan Ivšić.
According to the law, the accent was retracted from the word-final yers onto the preceding syllable. That syllable gained rising accent ("Slavic neoacute").[1] Compare:
In conservative Croatian dialects of Čakavian and partly Štokavian (e.g. Slavonian) this neoacute is preserved as special tone in long syllable, and is marked with a tilde.
Retraction also occurred if Proto-Slavic accent (but not acute) was carried by a secondarily lengthened syllable, e.g. on verbs in *-iti. Compare:
Also, Ivšić's law explains the acute on nouns such as sũša (Slavonian Štokavian speeches), vȍlja (with shortened neoacute).
Borrowings from other languages show that Ivšić's law operated after Dybo's law. Compare:
Standard Štokavian Croatian has merged the reflex of neoacute with the reflex of Proto-Slavic circumflex, i.e. the long falling accent (cf. standard Croatian krȃlj), but the neoacute has still been preserved as a distinct prosodical feature in Čakavian and Old Štokavian (e.g. Posavian) speeches.