String of Plurals
Today's agenda includes an examination of some singular plurals. The data is in. The criteria for using singular verbs with traditionally plural nouns have been set. However, the media doesn't always agree with academia.
You all remember the basic rules for creating a plural noun: simply add s, es, or ies, based on how the word ends. Of course, English sometimes follows the rules of other languages, such as Latin. For example, each sentence in the first paragraph contains a plural noun that ends in a. To make matters more confusing, some of these originally-plural nouns are matched with singular verbs. Let's take a closer look.
agendum / agenda
I don't recall ever seeing the word agendum anywhere but in a dictionary. Yet, according to its original meaning, agendum is a singular noun for something that needs to be done. The plural form, agenda, refers to multiple tasks.
However, any number of tasks can be put on a to-do list. And list is a singular noun. So it's become perfectly acceptable to match agenda with a singular verb, as in "An agenda is distributed at the start of every meeting."
In fact, since there can be more than one list, it's also become acceptable to "bi-pluralize" agenda by adding an s. For example, "They have competing agendas."
datum / data
As with the previous pair, the singular form, datum, is virtually extinct. Recent dictionaries will tell you that data can take a singular or plural verb. So which should you use?
Consider whether you're using data to refer to the information (singular) as a whole or to the different facts (plural) being presented. For example, use a singular verb to say "The data confirms our hypothesis." Use a plural verb to explain "These data show conflicting results."
By the way, while it's acceptable to consider different agendas, you'll get in trouble if you try to present datas.
criterion / criteria
While you may occasionally come across criteria matched with a singular verb (as agenda and data may be), that usage isn't accepted by most authorities. So remember that a criterion is just one standard to meet, while criteria include multiple standards to follow.
medium / media
As a noun, medium may refer to a method of mass communication, for example, "TV is a medium for delivering news and entertainment."
When referring to more than one delivery method, use media as the plural noun. For instance, "The media are competing for ad dollars." You may see media referring to a single method of communication, as in "The Internet is a relatively new media." But authorities typically consider such usage incorrect.
However, media is accepted as a singular or plural noun when referring to the journalists, broadcasters, and/or others in charge of the content being delivered. If you're referring to "the press" as one group, use a singular verb, as in "The media jumps at any hint of scandal." If you're referring to various members of the press, use a plural verb, as in "The media have shown varying levels of interest in that story."
Oh, and just in case you're wondering: if you want to consult more than one psychic, those mediums generally insist on being paid in advance.