From Longman Dictionary of Contemporary Englishrustyrust‧y /ˈrʌsti/ ●○○ adjective 1 
HCMmetal that is rusty is covered in rust a rusty nail a new metal that will never go rusty2 PRACTISE/PRACTICEif you are rusty, you are not as good at something as you used to be, because you have not practised it for a long time My French is a bit rusty.
HCMmetal that is rusty is covered in rust a rusty nail a new metal that will never go rusty2 PRACTISE/PRACTICEif you are rusty, you are not as good at something as you used to be, because you have not practised it for a long time My French is a bit rusty.Examples from the Corpus
rusty• I hadn't practiced for a long time, so I was really rusty.• My Spanish is pretty rusty.• We haven't played in a long time, we might be a little rusty.• an old rusty bicycle• The bicycle looked a bit rusty, but it worked.• It was attached to a rusty chain hidden in the bracken.• There was an old rusty freighter out in the bay that was used as a buoy.• I turn a rusty handle in the part of my brain that handles mental arithmetic.• I opened the rusty iron gate and walked up the path.• As soon as the adventurers enter, two of the Skeletons will rip their rusty iron manacles out of the floor and attack.• Appalled by rusty, jagged equipment, she proposed replacing it in 1987.• I was rusty, my timing was a little off.• A rusty old car had been abandoned at the side of the road.• I imagined dead mice and old wires curled recklessly in the walls, rusty pipes among antique fixtures.• The rusty wheels of his memory began to work.go rusty• Maybe they're still there - a great heap of them going rusty and covered in dust and cobwebs.• The ball-hitch mechanism seemed to have gone rusty and jammed up since it was last used. 