"an illicit association with his secretary"
"an illegitimate seizure of power" "illicit trade" "an outlaw strike" "unlawful measures"
My unhappy son had formed an illicit connection with a young woman.
The..trout..were taken by..illicit means without respect for season or ownership.
牛津高阶第八版
美国韦氏词典
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维基百科 (自由的百科全书)