Elan Yash

Elan is head of design and tech. He's also a contributor at Grammarflex.

What’s the Plural of Referendum?

A referendum which describes the “submitting of a question to the voters as a whole”, is referendums as a plural noun.

Vertex, which is a Latin word meaning “highest point”, has two plural noun forms, vertices and vertexes.

Bacteria is a plural noun, and comes from Latin. Bacterium is singular.

The singular of data is datum. Data is plural, and the more commonly used of the two.

The plural of radius is radii or radiuses. Radius is singular.

Stimulus, like other Latin nouns that have made it to Modern English (syllabus, locus, focus, radius,) uses -I as a plural noun, stimuli.

‍Media (pl. n.) singular is medium, in most cases. Media can be used as a mass noun, or non-count noun, which only use singular noun forms.

Apex meaning, “the tip, point, or summit”, comes from Latin; originally, its plural is apices. Apexes has come to be accepted over time.

Species is plural for species. Species is already a plural noun.

Just like salmon, tuna and cod, trout stays the same in both the singular and plural case.