Pirate - piracy

Note that both nouns pirate (the active person, the agent noun) and piracy (the name of the activity) are pronounced with the diphthongal '-i-':

• 'PIE-ret, IPA: /ˈpaɪ rət/
• 'PIE-ress-y', IPA: /ˈpaɪ rəs ɪ/

They are different from the superficially similar pair, privacy and private.