fancu -fanc- gismu

x1 is a function/single-valued mapping from domain x2 to range x3 defined by expression/rule x4.

See also mekso, bridi.

In notes:

bridi
x1 (text) is a predicate relationship with relation x2 among arguments (sequence/set) x3
fatfrika'efancu
x1=fan1=fr1 is a bijective function / isomorphism from x2=fan2 to x3=fan3, with inverse x4, in system / category x5; x1 has an inverse; x1 is a function that is injective and surjective; x2 and x3 are isomorphic; x1 is invertible.
fatkajyfancu
x1=fc1 is an inverse function from domain x2=fc2 to range x3=fc3 defined by original function x4=f4
funtiio
x1 (plural of ordered pairs) is an exhaustive set (possibly infinite) of inputs/outputs defining a unary function which yields result x3 when given input x2; x1(x2) = x3
integrale
x1 (number) is the integral (limit) of function x2
mekso
x1 [quantifier/expression] is a mathematical expression interpreted under rules/convention x2.