On 10/12/22, G. Branden Robinson <g.branden.robinson@xxxxxxxxx> wrote: > Similarly, we say "thirty year-old bug" The singular might be unambiguous that way, but the hyphen disambiguates the plural: "thirty year-old bugs" is 30 bugs that are a year old, whereas "thirty-year-old bugs" is an unspecified number of bugs that are 30 years old. Given that, omitting the first hyphen in the singular case looks odd: for consistency it ought to be applied there too, since you're clearly not talking about "30 bug." Plus, that hyphen is conventionally used even in noun form: "Stop acting like a thirty-year-old."
