I. ˈal-fə noun
Etymology: Middle English, from Latin, from Greek, of Semitic origin; akin to Hebrew āleph aleph
Date: 13th century
1. : the 1st letter of the Greek alphabet — see alphabet table
2. : something that is first : beginning
3. : alpha wave
4. : alpha particle
II. adjective
Date: 1863
1. : closest in the structure of an organic molecule to a particular group or atom — symbol α
α-substitution
2. : socially dominant especially in a group of animals
an alpha male
3. : alphabetic