hi-fi /ˈhaɪˌfaɪ/noun 2adjective 1forms 3 noun2 •High fidelity. •An electronic device used to play recorded sound, especially music. adjective1 •(India) modern, fashionable, hi-tech.If buses could fly: Hi-fi idea to fix traffic woes back on table — 2024 formshi-fis · more hi-fi · most hi-fi