From The Collaborative International Dictionary of English v.0.48 :
Algol \Al"gol\, n. [Ar. al-gh[=u]l destruction, calamity, fr.
gh[=a]la to take suddenly, destroy.] (Astron.)
A fixed star, in Medusa's head, in the constellation Perseus,
remarkable for its periodic variation in brightness.
[1913 Webster]