grouse (3) n. (frequently with the intensifier extra) Aust. very good of its kind. [20th c.: origin unknown]
Two things stuck out from this entry. First, the intensifier extra: I have to say I don't remember it being used 'frequently' to intensify an already intense word, but boy, what a compliment. To call something or someone extra grouse - is there any higher praise possible? ('Knock off work early? That, my friend, is an extra grouse notion.')
The second thing that struck me was the little n. right at the start there. It's not a typo - at least not on my part (I might be wrong, but I'm sticking by my definition at the start of grouse as an adjective). But it got me thinking about how one could use grouse as a noun. I thought it could be used in the same way 'star' is used to talk about people who are, well, grouse.
'Thanks for editing my story, mate - you're a grouse.'
But in this example, either you're left waiting for more - a grouse what? - or it sounds too much like 'louse' to be complimentary.
So I may have to beg to differ with the ACOD on this one. Grouse is grousest as an adjective.
(For those wondering what the other two entries were:
grouse (1) n. (pl. same) any of various game birds of the family Tetraonidae, with a plump body and feathered legs.
grouse (2) v. & n. colloq. * v.intr. grumble or complain pettily. * n. a complaint.)