Media - medium

The word medium is a noun. In origin, it is a Latin word in the singular form. The plural in Latin is formed regularly, though it looks irregular in English - media, pronounced 'MEED-i-uh', IPA: /ˈmiːd ɪ ə/. Academic readers will sneer if you use the word 'mediums, or the 'phrase 'a media'. (For a proper noun spelled identically, see Medea - Media.)

For other examples of plurals that are irregular in English, see the table at Loan words - singular, which lists some foreign words most commonly used in our language in their singular form, or in both singular and plural forms as dictated by their meaning; and the other table at Loan words - plural which lists the foreign words used mostly in their plural forms.