USEL: A Universal Symbolic Executable Language Grounded in Natural Semantic Metalanguage Primes

We present USEL (Universal Symbolic Executable Language), a programming language whose vocabulary is derived from the 65 semantic primes identified by Natural Semantic Metalanguage (NSM) research. Over five decades of cross-linguistic fieldwork has established that these 65 concepts exist as irreducible lexical items in every natural language studied to date, spanning more than 300 typologically diverse languages. USEL treats these primes as the atomic building blocks of a new kind of language: one that is simultaneously human-universal, child-readable from age five, natively parseable by large language models, and executable as real code. The language compiles a single source representation to five targets: JavaScript, Python, WebAssembly text format, natural language sentences, and a canonical USEL text notation. A projectional tile-based editor enforces grammar rules at the structural level, making syntactic errors physically impossible to construct. The reference implementation comprises 11,545 lines of TypeScript across 31 source files, with 184 passing tests. Source code: https://github.com/kitfoxs/usel-lang