We present IRDL, a dialect for representing IR definitions. IRDL lets users define dialects in a declarative style, allowing for a dynamic registration of dialects using dynamic dialects, which were recently introduced in MLIR. Additionally, we will present two lower-lever dialects, IRDL-SSA and IRDL-Eval, and their respective lowerings, which enable interesting optimizations on the operation verifiers, which ODS does not currently handle. We hope that with IRDL, we will simplify the generation of dialects through metaprogramming, or external languages, like Python.