Today's Word: galaxy

galaxy: The base of galaxy is derived from gala, Greek for "milk." Hence galactorrhea, the spontaneous flow of milk from one's jubblies. Of course, we're more accustomed to seeing lacto- as a "milky" prefix. Notice that galacto- is just one syllable larger than lacto-; that isn't a coincidence. The Latin lacto- comes from the Greek.

According the Merriam-Webster's great Collegiate Dictionary, the earliest known use of galaxy comes from Chaucer sometime before 1385 in a poem called The House of Fame:

Se yonder, loo, the Galaxie,
Which men clepeth the Milky Wey,
For hit is whit.

(See yonder, lo, the galaxy
Which men call the Milky Way
For it is white.)

Clearly, then, the name Milky Way was common at least in England at this time. Galaxy wasn't used as a generic term for other massive star systems until the 19th century.