- A lake.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Examples from the Web for lacus
The spot was afterwards covered by a marsh called the Lacus Curtius.
Now the gradation in size, from the Lacus Solis down to the smallest oasis of Lowell, is a complete one.Are the Planets Inhabited?
E. Walter Maunder
Lacus Juturnæ is a four-sided basin with a pillar in the middle, on which rested a marble altar decorated with figures in relief.Outlines of Greek and Roman Medicine
James Sands Elliott
Lacus a Lake, a little sea with in the land hauing riuers running into it, or out of it, or both.A Briefe Introduction to Geography