1
- the first letter of the Greek alphabet (Α, α), transliterated as 'a'希腊字母表中第一个字母（译写为a）。
1.1
- as modifier denoting the first of a series of items or categories, e.g. forms of a chemical compound甲, α项, α类（一系列项目、分类中的第一位, 如化合物的第一种形式）：
alpha interferon
α干扰素
the α and β chains of haemoglobin.
α和β链血红蛋白。
1.2
- Brit. a first-class mark given for an examination paper or piece of school or college work〈英〉（学校考试成绩或作业）Α等, 甲等：
he had been awarded alpha double plus.
他得了Α++的好成绩。
1.3
- short for ALPHA TEST.ALPHA TEST的简称。
1.4
Alpha
followed by Latin genitive Astronomy the first (typically the brightest) star in a constellation【天文】α星（星座中第一颗星, 多为最亮的星）：Alpha Orionis.
猎户座α星。
1.5
- as modifier relating to alpha decay or alpha particles与α衰变（或α粒子）有关的：
an alpha emitter.
α粒子发射体。
1.6
- as modifier denoting the dominant animal or person in a particular group（人或动物特定群体中的）头领; 首领：
Turner soon proved to be the alpha male.
特纳很快便证明是男人中的头儿。
2
- a code word representing the letter A, used in radio communication（无线电通信中字母A的代码词）Α, α.
1.1
α
a plane angle（平面角符号）α角。
1.2
α
angular acceleration（角度增加符号）α.
1.3
α
Astronomy right ascension【天文】赤经。
短语
alpha and omega
1
- the beginning and the end (especially used by Christians as a title for Jesus)首尾, 始终（尤指基督徒对耶稣的称呼）。
1.1
- the essence or most important features本质, 要素。
词源
via Latin from Greek.