Pronunciation: (al'fu),[key] —n. 1. the first letter of the Greek alphabet (A, α).
2. the vowel sound represented by this letter.
3. the first; beginning.
4. (cap.) Astron.used to designate the brightest star in a constellation.
5. Chem.one of two or more isomeric compounds.
6. the first in a series of related items: frequently used in chemistry and physics.
7. Chiefly Brit.a mark or grade corresponding to an A. Cf. beta (def. 8), gamma (def. 9).
—adj. 1. (esp. of animals) having the highest rank of its sex in a dominance hierarchy: the alpha female. 2. Chem.pertaining or linked to the carbon atom closest to a particular group in an organic molecule.