半衰期 Traditional form: 半衰期 Pinyin (reading): bànshuāiqī Definitions: half-life Characters: 半 - half; semi-, incomplete 衰 - weak, feeble; to decline, to falter 期 - a period of time; date, time; phase Traditional characters: 半 - half; semi-, incomplete 衰 - weak, feeble; to decline, to falter 期 - a period of time; date, time; phase