Are there any words that are irregular (disregarding the liaisons at the end of the words)? For example words with "-ss-" (between vowels) being pronounced like [z] or "-s-" (between vowels) being pronounced like [s].
I wouldn't consider "monsieur" (masc. sing.) irregular because historically it was "mon sieur" in the past with its pronunciation evolved to today.
Just a curiosity. I hope what I wrote is clear.