Objective-C

http://en.wikipedia.org/wiki/Objective-C suggests: "Objective-C is a general-purpose, high-level, object-oriented programming language that adds Smalltalk-style messaging to the C programming language. It is the main programming language used by Apple for the OS X and iOS operating systems and their respective APIs, Cocoa and Cocoa Touch. In Objective-C one does not simply call a method; one sends a message."

http://en.wikipedia.org/wiki/Smalltalk suggests: "The message is the most fundamental language construct in Smalltalk. Even control structures are implemented as message sends. Smalltalk adopts by default a synchronous, single dynamic message dispatch strategy (as contrasted to a synchronous, multiple dispatch strategy adopted by some other object-oriented languages)."