DumpSave

DumpSave["file.mx", symbol] writes definitions associated with a symbol to a file in internal Wolfram System format.

DumpSave["file.mx", "context\"]` writes out definitions associated with all symbols in the specified context.

DumpSave["file.mx", {obj1, obj2, ...}] writes out definitions for several symbols or contexts.

Examples

Save a function definition to a file:

f[x_] := x^2;
DumpSave["myfunction.mx", f]
(* {f} *)

Load it back:

Get["myfunction.mx"]
f[3]
(* 9 *)

Please visit the official Wolfram Language Reference for more details.