- the first letter of the Greek alphabet (?, ?)
- the beginning of anything
- [A-]Astron. the name assigned to the brightest star in each constellation: followed by the constellation's name in the genitive case, as Alpha Centauri
Origin of alphaClassical Greek from northwestern Sem: compare Classical Hebrew (language) alef, aleph
- designating or of the socially dominant member of a group, esp. of a group of animals: the alpha male
- Chem. designating the first of two or more positions in which the substituting atom or radical appears relative to some particular carbon atom in an organic compound: usually written ?-: the other positions, in order, are beta (?-), gamma (?-), delta (?-), etc.