Classical Plurals in Academic Writing

Read and use the Greek and Latin plural forms common in science and scholarship.

Many academic nouns kept their Greek or Latin plurals instead of taking a simple -s. Greek -on becomes -a: criterion, criteria; phenomenon, phenomena. Greek -is becomes -es: hypothesis, hypotheses; analysis, analyses; thesis, theses. Latin -um becomes -a: datum, data; curriculum, curricula; medium, media. Latin -us often becomes -i: nucleus, nuclei; stimulus, stimuli. Latin -a becomes -ae: vertebra, vertebrae; formula can be formulae or formulas. Worked example: 'One criteria for the grant is originality. ' The subject is singular, so the correct form is 'one criterion.

' Watch for 'data': in scientific writing it is often treated as plural ('the data are'), but everyday and much professional usage treats it as a mass noun ('the data is'). Follow the style your discipline uses. Recognizing these plurals also helps you count: 'two hypotheses' means two separate testable claims.

• 1-on to -a, -is to -es, -um to -a, -us to -i, -a to -ae.
• 2Criterion and phenomenon are singular; criteria and phenomena are plural.
• 3Usage of 'data' varies by discipline.