Term ambiguity — the challenge of having multiple potential meanings for a keyword or phrase — can be a major problem for search engines. Contextual information is essential for word sense disambiguation, but search queries are often limited to very few keywords, making the available textual context needed for disambiguation minimal or non-existent. In this paper we propose a novel system to identify and resolve term ambiguity in search queries using large-scale user behavioral data. The proposed system demonstrates that, despite the lack of context in most keyword queries, multiple potential senses of a keyword or phrase within a search query can be accurately identified, disambiguated, and expressed in order to maximize the likelihood of fulfilling a user's information need. The proposed system overcomes the immediate lack of context by leveraging large-scale user behavioral data from historical query logs. Unlike traditional word sense disambiguation methods that rely on knowledge sources or available textual corpora, our system is language-agnostic, is able to easily handle domain-specific terms and meanings, and is automatically generated so that it does not grow out of date or require manual updating as ambiguous terms emerge or undergo a shift in meaning. The system has been implemented using the Hadoop eco-system and integrated within CareerBuilder's semantic search engine.