Webster’s Revised Unabridged Dictionary · 1913
Confocal
Con·fo′cal (·fō′kal), a. (Math.) Having the same foci; as, confocal quadrics.
Webster’s Revised Unabridged Dictionary · 1913
Con·fo′cal (·fō′kal), a. (Math.) Having the same foci; as, confocal quadrics.