  In this work, we explore idiomatic language processing with Large Language
Models (LLMs). We introduce the Idiomatic language Test Suite IdioTS, a new
dataset of difficult examples specifically designed by language experts to
assess the capabilities of LLMs to process figurative language at sentence
level. We propose a comprehensive evaluation methodology based on an idiom
detection task, where LLMs are prompted with detecting an idiomatic expression
in a given English sentence. We present a thorough automatic and manual
evaluation of the results and an extensive error analysis.
