Posted on November 13, 2021 by WillemSaturday/ a mushroom, very fly fly3 adjective INFORMAL adjective: fly; comparative adjective: flyer; superlative adjective: flyest NORTH AMERICAN stylish and fashionable. “Where’d you get that fly shirt?” The fly agaric mushrooms popping up in my back yard were smaller than usual, this year. A fly agaric mushroom, Amanita muscaria. This is one 5 inches across. The squirrels gnawed at it for a bit, and then left it alone.