1 (of food etc) not fresh and therefore dry and tasteless: stale bread.
az: boyat, köhnəlmiş
ru: несвежий; чёрствый
2 no longer interesting: His ideas are stale and dull.
az: bayağı, köhnəlmiş
ru: избитый, затасканный
3 no longer able to work etc well because of too much study etc: If she practises the piano for more than two hours a day, she will grow stale.
az: yorğun
ru: выдохшийся