Irregular words are words in which at least one correspondence
between grapheme and phoneme is not regular, is not straightforward.
A few examples of irregular words are 'said',
'yacht', 'knight' with a 'k' at the beginning,
'gift', 'white', 'echo', 'role', 'busy', 'much', 'sure'.
These words, if you think about it,
what path are you going are you going to use to read these words?
Since they are irregular, you cannot use the phonological decoding rule,
because you are going to make mistakes, and I'll come back to these mistakes.
You can only use the lexical stored knowledge.
You need to know that said is pronounced.
'sed' and not 'say-eed', for example.
So, you will have to use the direct access path for these irregular words.