alpha

noun

• 1the first letter of the Greek alphabet (Α, α), transliterated as ‘a’.
• [as modifier] denoting the first of a series of items or categories, e.g. forms of a chemical compound:the α and β chains of haemoglobin
• British a first-class mark given for an examination paper or piece of school or college work:he had been awarded alpha double plus
• [as modifier] Zoology & Sociology denoting the dominant animal or human in a particular group:the pack is a tightly knit, highly organized group, led by an alpha wolfSee also alpha male.
• [as modifier] informal denoting a person who has a dominant role or position within a particular sphere:take turns cooking for each other if one of you is too much of an alpha chef
• short for alpha test.
• (Alpha) [followed by Latin genitive] Astronomy the first (typically the brightest) star in a constellation:Alpha Orionis
• [as modifier] relating to alpha decay or alpha particles:an alpha emitter

• 2a code word representing the letter A, used in radio communication.

symbol

• (α) a plane angle.
• (α) angular acceleration.
• (α) Astronomy right ascension.