If someone is green with envy, they are jealous about something.
My sister has just bought a brand new car – I'm green with envy.
Sophie was green with envy when she heard that Alice had won the lottery.
Take a look at my engagement ring, it's beautiful – I bet you'll be green with envy!
Don't confuse it with
If you look green around the gills, you look unwell.
I think we should take Alexander to the doctor – he's looking a bit green around the gills.
I can't travel by boat, it makes me feel really green around the gills.
The Star Trek convention, held in London last week, broke the World Record for the largest gathering of fans dressed as characters from the series, including alien characters. The event also featured the UK's first Klingon wedding, when a Swedish couple, dressed as Klingons, exchanged vows and swore to "unite against all their opponents".