To speak with an accent or dialect (to have a nonstandard pronunciation); also to become corrupted or altered in pronunciation or form.
彼は子どものころから方言で訛っているので、標準語とは少し違う発音をする。
He has spoken with a dialect since childhood, so his pronunciation differs somewhat from standard Japanese.
古い文献を読んでいると、時代とともに言葉が訛っているのが分かる。
When reading old texts, you can see how words have become altered over time.
長年の海外生活で、彼の発音も少し訛ってしまった。
After many years living abroad, his pronunciation has become a bit accented.
地方の言葉が混じって標準語が訛ることは珍しくない。
It's not uncommon for standard speech to acquire local dialectal features.