非典

Short for 非典型肺炎 ('atypical pneumonia'), the Chinese name for the SARS coronavirus that emerged in Guangdong in late 2002 and spread globally in 2003. The term lived on in Chinese collective memory long before COVID-19 (新冠) — and a common piece of 2020 commentary was '比非典更严重' ('worse than SARS').

memory

非 (not) + 典 (typical, here short for 典型) = 'a-typical' (pneumonia). Chinese abbreviation logic: drop the descriptive noun 肺炎 and keep just the modifier.