The paper proposes that human language includes a universal “noun slot” capacity: regardless of whether an expression is originally a verb, adjective, adverb, preposition, conjunction, or another category, speakers can often reinterpret or derive it into a noun-like entity that can occupy core grammatical positions such as subject and object. The central claim is that “thing-like” representation is a default cognitive option in grammar and meaning: qualities, events, relations, and even discourse particles can be coerced into entities that the mind treats as referable objects. To argue for this, the paper introduces a method called the Reverse Entailment Diagnostic (RED). The idea is simple: apply a nominalizing strategy (for example, possessive patterns, nominalizers, or “the X” type structures), then test whether the resulting form becomes interpretable and can function in a noun position. If it does, this “reverse-entails” that the original expression has latent nominal potential. The paper illustrates RED with recurring examples across multiple languages and extends the discussion beyond the usual noun–verb alternations to more marginal categories, suggesting that the noun slot is a broad organizing principle rather than an exception-driven patch. Theoretically, the paper frames this proposal as a challenge to rigid lexical-category assumptions and as more compatible with approaches where category can be assigned by structure or construction (rather than fixed in the lexi