Final answer:
The word that defines 'inveterate' in this sentence is 'habitual'.
Step-by-step explanation:
The word 'inveterate' means 'habitual' or 'long-standing'. In the context of the sentence, it describes Ferdinand as someone who has been a liar for a long time. It implies that lying has become a deeply ingrained habit for him. Therefore, the word that defines 'inveterate' in this sentence is habitual.
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