Consonants are generally more stable. However, the Indo-European voiced aspirates "bh, dh, gh, gwh" are not maintained, becoming "f, f, h, f" respectively at the beginning of a word, but usually "b, d, g, v" elsewhere. Non-initial "dh" becomes "b" next to "r" or "u", e.g. "*h₁rudh-" "red" > "rub-", e.g. "rubeō" "to be red"; "*werdh-" "word" > "verbum". "s" between vowels becomes "r", e.g. "flōs" "flower", gen. "flōris"; "erō" "I will be" vs. root "es-"; "aurōra" "dawn" < *"ausōsā" (cf. Germanic "*aust-" > English "east", Vedic Sanskrit "uṣā́s" "dawn"); "soror" "sister" < "*sosor" < "*swezōr" < "*swésōr" (cf. Old English "sweostor" "sister").