This study explores L2 learners' awareness of meaning of L2 conventional expressions and the effect of form-meaning associations on the use of the expressions in L2 pragmatics. Definitions and examples were elicited through an aural Vocabulary Knowledge Scale modified for expressions. Elicited definitions were used to explore the meanings that learners assign to conventional expressions and learners' examples were used to investigate the use to which they put them in conversation. One hundred and thirteen learners participated in a 22-item task in which all conventional expressions were presented aurally. Learner awareness of the meaning of conventional expressions seems likely to play a role in whether learners use an expression, and which expression among related expressions they use to the exclusion of others. Moreover, plausible meanings may be gradually associated with a conventional expression and refined rather than acquired at the same time as the form of the expression.