Word of the Day


© Alamy Stock Photo
Liz Potter
Written by Liz Potter


the scientific study of infectious diseases and their causes

View the full definition in the Macmillan Dictionary.

Origin and usage

The noun epidemiology is formed from two words of Greek origin, the noun ‘epidemic’ and the  suffix -logy or -ology, used to form words that refer to a branch of knowledge. It was first used in English in the late 19th century.


Words can come into prominence very suddenly and dramatically as a result of events. A case in point is epidemiology, which was quietly minding its business as one of the less well-known medical specialisms when it was catapulted into the spotlight by the Covid-19 pandemic. Epidemiology and its related terms are on everyone’s lips; epidemiologists appear on news programmes to explain their science and its insights to a lay audience. People can sometimes struggle to get their tongues round unfamiliar terms, and this is seemingly the case with epidemiological, the related adjective to epidemiology. ‘Epidemiological‘ is an entry in the Open Dictionary and its pronunciation follows the stress pattern of similar words. In these words the main stress falls on the antepenultimate or third-to-last syllable; when you add syllables for the adjective and adverb, the stress shifts accordingly. So biology is pronounced /baɪˈɒlədʒi/, biological /ˌbaɪəˈlɒdʒɪk(ə)l/; similarly archaeology /ˌɑː(r)kiˈɒlədʒi/ and archaeological /ˌɑː(r)kiəˈlɒdʒɪk(ə)l/; and epidemiology /ˌepɪdiːmiˈɒlədʒi/ follows the same pattern, with epidemiological pronounced /ˌepɪˌdiːmiəˈlɒdʒɪk(ə)l/. Note that it doesn’t matter how many syllables precede the main stress, it always falls on the third from last syllable.


The work of epidemiology is related to unanswered questions, but also to unquestioned answers.
(Patricia Buffler)

Related words

endocrinology, embryology, haematology, immunology

Browse related words in the Macmillan Thesaurus.

About the author

Liz Potter

Liz Potter

Leave a Comment