# Why is it called Kernel?

In the Fredholm/Volterra Integral equation, the function K(x,t) is called as KERNEL. But why should we call it with a new name 'kernel' rather than calling 'function' Itself ?

• Closely related, What exactly is an integral kernel?, on which a Comment makes the point that applying such an integral operator might involve "loss of information". The word kernel is used in other contexts in mathematics to directly denote such a loss, through identifying what elements are mapped to zero. – hardmath Sep 20 '17 at 2:15
• Earliest Known Uses of Some of the Words of Mathematics (K) says the use in integral equations is older than, and apparently unrelated to, the use in algebra. It apparently comes from Fredholm's French "noyau", via Hilbert's translation to the German word "Kern". – Chappers Sep 20 '17 at 2:31