Complex sentence: Deep orthographies are writing systems that do not have a one-to-one correspondence between sounds (phonemes) and the letters (graphemes) that represent them, such as those of English or Arabic.
Split into simpler sentences: Deep orthographies are writing systems that do not have a full correspondence between the spoken phoneme and the written grapheme. Where there is not a one-to-one correspondence between the letters and the phonemes in the language, such as those of English or Arabic.