Subject-verb (SV) agreement helps listeners interpret the number condition of ambiguous nouns ("The sheep is/are fat"), yet it remains unclear whether young children use agreement to comprehend newly encountered nouns. Preschoolers and adults completed a forced choice task where sentences contained singular vs. plural copulas ("Where is/are the [novel noun(s)]?"). Novel nouns were either morphologically unambiguous ("tup/tups") or ambiguous (/geks/ = singular: "gex" / plural: "gecks"). Preschoolers (and some adults) ignored the singular copula, interpreting /ks/-fnal words as plural, raising questions about the role of SV agreement in learners' sentence comprehension and the status of "is" in Australian English.