The present study investigated advanced Croatian EFL learners’ knowledge of five meanings of the English nominal (deverbal) suffix -er. It probed their ability to comprehend and produce corpus-rare and presumably unentrenched -er nouns in their prototypical agent and instrument meanings and their non-prototypical patient, locative, and causative meanings. It was hypothesized that participants would deal effortlessly with agent and instrument meanings of the low-frequency nouns since the corpus-attested high type frequency of -er agents and instruments, among others, suggests the existence of productive corresponding schemas. We hypothesized that participants would struggle with patient, locative and causative meanings of the low-frequency nouns since the corpus-attested low type frequency of the three functions arguably does not support their association with -er. A recognition and a production test were administered to two separate groups of English majors at a Croatian public university (n = 131). Results confirm general usage-based predictions about better performance with low-frequency agent and instrument -er nouns. However, a detailed examination reveals unexpected results, which confirm that frequency, however important, is not the only factor to include in a future model of EFL learners’ derivational proficiency.
