What is the term for a complete set of known commands in a machine language?

The term for a complete set of known commands in a machine language is "Instruction List." An Instruction List encompasses all the instructions that a given machine architecture can execute. This includes various operations such as arithmetic calculations, data movement, control operations, and more, which are crucial for programming at a low level.

In contrast, "Lexis" refers to the vocabulary of a language (often used in linguistics) and doesn't apply to machine languages specifically. "Syntax" pertains to the rules that define the structure of valid statements in a programming language, guiding how code is written but not representing the complete set of commands. "Semantics," on the other hand, deals with the meanings of those statements and instructions—what they actually do when executed—but it doesn't enumerate the specific commands themselves.

Understanding the distinction between these concepts is essential for grasping how programming languages and machine languages operate.