贝塔射线 bèitǎshèxiàn beta ray Origin Definitions Defs Strokes Stroke Words Sentences Sents 贝塔 貝塔 bèitǎ beta beta, the second letter of the Greek alphabet射线 射線 shèxiàn noun ray (physics) A stream of high-energy particles or electromagnetic waves, such as X-rays or alpha rays.