What is the name for f(ab)=f(b)f(a)?

[mnb96]

Hi,
a morphism f is a structure preserving mapping, and under a morphism the following holds: f(ab) = f(a)f(b)

what is the name for a similar concept but where instead we have:
f(ab) = f(b)f(a)

This happens for example for the element inversion in a group: $$(ab)^{-1}=b^{-1}a^{-1}$$.
I found it somewhere, some time ago, but I cannot find it anymore. I thought it was something like antimorphism, but I would not bet a cent on it.

 

[mnb96]

ok...I found it: it was anti-homomorphism