Nouns

(n)alphathe 1st letter of the Greek alphabet
(n)alphathe beginning of a series or sequence“the Alpha and Omega, the first and the last, the beginning and the end” (The Bible, Revelations 22:13)

Adjectives

(s)alphafirst in order of importance“the alpha male in the group of chimpanzees”, “the alpha star in a constellation is the brightest or main star”
(s)alphaearly testing stage of a software or hardware product“alpha version”