o can raise to ó in certain pronouns: cóś (coś) before liquids, and in many imperative forms: chódź (chodź).
Historically śrz-, źrz- change to rś-, rź-, but śr- and źr- are more common.
Other instances of consonantal prothesis before word-initial vowels occur, but are rare.
strz, trz, zdrz, drz, st, stn simplify to szcz(sz), cz(sz), żdż(ż), dż(ż), s, sn, sf.
rst, rsk, rszt, rz, rż, rść tend to simplify in various ways, usually with the loss of r. A change of s, ś to ss, śś, sc, ść occurs in many words.
[3] Many noun forms do not show ablaut, the result of levelling: mietła (miotła).
Often mobile -e- is kept in inflections and added in some clusters: z bezu, mechu (z bzu, mchu); łoter (łotr).
[3] The adverb comparative and genitive/dative feminine singular ending of pronouns and adjectives -ej shifts to -i/-y.
Many verb forms do not show ablaut, the result of levelling: wieze (wiozę).
Many first person present/future verb forms have hardened consonants via analogy: złape (złapię).
A final -k and -j is added to many pronouns and adverbs: nikogój (nikogo), jeszczek (jeszcze).