Sirius (n.) Look up Sirius at Dictionary.com
brightest star, late 14c., from Greek Seirios, literally "scorching." Probably so called from its ancient heliacal rising at the summer solstice (see dog days). An Egyptian name for it was Sothis.
Homer made much of it as [Kyon], but his Dog doubtless was limited to the star Sirius, as among the ancients generally till, at some unknown date, the constellation was formed as we have it, -- indeed till long afterwards, for we find many allusions to the Dog in which we are uncertain whether the constellation or its lucida is referred to. [Richard Hinckley Allen, Canis Major in "Star Names and Their Meanings," London: 1899]
Also cf. dog star.