A retail company is building a RAG-based product support assistant on Microsoft Foundry. During testing, users report that keyword searches return technically relevant documents but often miss articles that describe the same problem using different wording (e.g., 'device won't power on' vs. 'unit fails to boot'). The team wants the retrieval layer in Azure AI Search to match on meaning rather than exact terms. Which Azure AI Search capability should they enable to address this?