Objective: To explore staff knowledge of delirium by eliciting meaning through descriptions of their experiences within a residential aged care facility (RACF). Methods: Six staff from one RACF in Australia participated in this qualitative study. Semi-structured individual interviews were conducted and analysed using Colaizzi's analytical framework. Results: The analysis revealed four themes: (i) absence of the word delirium; (ii) care based on intuition and automated actions; (iii) reliance on teamwork; and (iv) confusing delirium, depression and dementia. Conclusion: Delirium was absent from clinical discourse in the RACF. Although participants concluded that delirium was common, lack of knowledge led to under-assessment. Findings emphasise the need for staff education, informed assessment and clinical guidelines to better support staff care for residents.