Longman Dictionary of Contemporary English - brilliant

~1 adj 1 brilliant light or colour is very bright and strong  (The stage was flooded with brilliant light. | brilliant reds and blues) 2 extremely good, clever, or skilful  (Cox's performance was brilliant. | a brilliant idea)  (Hugh came up with a brilliant idea for a book.) 3 BrE excellent  ("How was your holiday?" "It was brilliant!") 4 very successful  (a long and brilliant career) - brilliantly adv ~2 n technical a precious stone cut with a lot of surfaces that shine