This study aims to evaluate the degree to which core and peripheral meanings of polysemous verbs are used in the English textbook Full Blast Plus 4 for upper secondary students and to determine the cognitive processes underlying their semantic extensions. Polysemy is common in natural languages; however, it has received limited research interest. This is because research on vocabulary prioritised breadth - the number of form-meaning pairings acquired by learners - over depth of vocabulary knowledge, which encompasses a broader range (...) of lexical features beyond basic form-meaning connections. Recent studies have begun to acknowledge the significance of polysemous senses in vocabulary education and learners’ lexical proficiency, especially from a cognitive linguistics perspective. Still, few studies have examined polysemous word senses in educational materials; therefore, this paper addresses this research gap. This mixed-method, corpus-based research uses Sketch Engine’s Word List and Concordance tools to compile a list of polysemous verbs and explore their meanings. The Concordance tool is also applied to find metaphorical senses, which are manually analysed to find incongruous vehicle verbs and their context or co-text and determine conceptual metaphors that underpin them. The findings show that the textbook under study does not offer opportunities to engage with less common or peripheral senses. In addition, despite the apparent neglect of conceptual metaphor in the textbook’s design, conventional conceptual metaphors underpin most peripheral and figurative senses of the verbs examined. The results have significant implications for comprehending, as well as applying, polysemy and underlying cognitive mechanisms in second and foreign language learning. (shrink)