Those Roman Plurals Are Roamin'

Rob Kyff on

Q. I've noticed that some publications are using "millenniums" in place of "millennia," e.g., "The mastodon lived millenniums ago." Same for "medium" and "media." Have the rules changed? -- Amy Robinson, Hartford, Connecticut

A. Ah, the rules. Remember those mastodon days when original Latin plural endings ruled the Earth? Today, not so much.

While the plural of "millennium" has traditionally been "millennia," the Brits have favored "millenniums" for decades, and we Yanks are following suit. Now, both forms are standard on this side of the pond.

Other Latin plurals that can be safely rendered either way include honoraria/honorariums, memoranda/memorandums, syllabi/syllabuses, moratoria/moratoriums, indices/indexes, curricula/curriculums, cacti/cactuses.

In some cases, we use the Latin plural for words used in scientific contexts, e.g., spectra, vortices, larvae, formulae, nebulae, antennae, yet we deploy the "s" plural when these words are used in everyday discourse, e.g., spectrums, vortexes, larvas, formulas, nebulas, antennas.

Some words almost always use their Latin plurals, e.g., algae, agenda, errata, data, bacteria, strata, stimuli, while other words usually add an "s," e.g., atriums, aquariums, stadiums, campuses, viruses, ignoramuses (as opposed to atria, aquaria, stadia, campi, viri and ignorami, respectively).

Another problem arises when some Latin plurals are mistakenly used as singulars, e.g., The candelabra (candelabrum) is on the piano. An infectious bacteria (bacterium) is causing the disease. She cracked a vertebrae (vertebra) in her back.


The Latin plurals "data" and "media" are used so often as singulars that doing so can no longer be considered an error. "Data," the plural of "datum," means "two or more pieces of information" and should technically be treated as a plural, e.g., "These data are impressive." But we often use it as a singular, e.g., "Patient health data is routinely sold to research companies." Likewise, the use of "media" as a singular has become acceptable, e.g., "The news media is under fire."

As for choosing the correct plural of "medium," the choice is tricky. The plural when referring to means of transference or communication is "media," but the plural when referring to clairvoyants or things of medium size is "mediums."

So a headline reporting that two tiny fortunetellers had disappeared after committing a crime would correctly read, "Small Mediums at Large."


Rob Kyff, a teacher and writer in West Hartford, Connecticut, invites your language sightings. Send your reports of misuse and abuse, as well as examples of good writing, via email to or by regular mail to Rob Kyff, Creators Syndicate, 737 3rd Street, Hermosa Beach, CA 90254.

Copyright 2019 Creators Syndicate Inc.


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