As "lousy" is a pejorative for someone or something being infested with lice, why is it pronounced with a "z" instead of an "s" sound?

OTOH, when a person is called a "louse," the "s" sound is used.

Doubtless most people who use the word (lousy) don't really know what they're saying, thus the mispronunciation, but how did it get started in the first place?

  • Have you done any research at all? Both Cambridge and Merriam-Webster stipulate that the "z" sound is the proper pronunciation, and not a mispronunciation.
    – Davo
    Dec 12, 2019 at 14:09
  • I'm not sure your meaning of lousy concurs with normal use. Where did you get this definition from? If you were infested with lice you would be lice-infested - link might not work everywhere. As a native BrE speaker, if I wanted to express something being louse-like I would probably say lous-ey pronouncing it the same as mousey or licey.
    – Smock
    Dec 12, 2019 at 14:15
  • +1 for your comment @user067531 Dec 12, 2019 at 20:18
  • It's because of the louzy English language! What else do you need to know?
    – Hot Licks
    Dec 12, 2019 at 21:13

1 Answer 1


As to why that sort of change happens in general: the /s/ in louse becomes intervocalic (it is now between vowels) in lousy and thus becomes more likely to trigger lenition. It adjusts to the sounds preceding and following it, which are both more sonorous and becomes voiced too. I think it's supposed to make the pronunciation slightly easier and is a common change observed in multiple languages.

For a historical perspective on this particular word, user067531's comment seems to be spot-on.

  • In the word lousy /'lawzi/, all segments are voiced. If it were pronounced with /s/ instead of /z/, voicing would have to be turned off and then on again in the middle of the word. This is possible, but it costs effort that is unnecessary (hardly anyone notices and nobody at all cares whether it's voiced or not), so it's usually simply ignored, until it becomes a habit, then a convention. Dec 12, 2019 at 15:55
  • it's done all the time in other languages (ex: Spanish), so maybe English speakers are lazy @JohnLawler Dec 12, 2019 at 20:17
  • @green_ideas so is lenition (e.g. Spanish)
    – noketchup
    Dec 12, 2019 at 22:40
  • Every language has its own pattern of sound formations and lenitions. Of course English speakers are lazy; so are all speakers. The principle of minimum effort is a constant in human behavior. Dec 12, 2019 at 23:03

Not the answer you're looking for? Browse other questions tagged or ask your own question.