Experienced in a particular field or activity. Knows the ropes already and doesn't need training or instructions.
In a restaurant kitchen;
Cook: How's the new dishwasher? Does he require babysitting?
Manager: No, he's seasoned. He worked two years at that barbecue place down the street.
The Urban Dictionary Mug
One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.
Buy the mug