from The American Heritage® Dictionary of the English Language, 4th Edition
- adj. Having the same focus or foci. Used of a lens.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. (mathematics) Having the same foci
from the GNU version of the Collaborative International Dictionary of English
- adj. Having the same foci.
from The Century Dictionary and Cyclopedia
- In mathematics, having the same focus: as, confocal quadrics; confocal conies.
- n. A figure having the same focus as another.
con- + focal (Wiktionary)