Lacuna

la-ku'na, n.; pi. -nm, -ne. A small opening, pit, or depre ion; blank space; vacancy; hiatus. {Bot.) The small pit or cup-shaped depre ion the top of the thallus of some lichens: a vacant between the cells of plants; an air-cell. {Anat.) small cavity or sac in a mucous membrane. Lacustral, Lacustrine. See under Lake.