verbum

Verbum, verbi is a second declension NEUTER noun, so the nominative and accusative singular are both verbum and the plural is verba. Its opposite number in Roman thinking is res: verbo against re, "in word" against "in fact", is a standing contrast in oratory and one of the surest ways to spot a Roman making a distinction.

Latin grammarians used verbum as their technical term for the part of speech that carries the action, and every European language that calls that thing a verb, verbe, verbo or Verb is quoting them. The phrase verbi gratia, "for the sake of an example", is the older cousin of exempli gratia; ad verbum and verbatim both mean "word for word".

One frequency note. Verbum ranks this high partly because our corpus takes in the Vulgate and later Christian writing, where Verbum with a capital renders the Greek Logos of John's gospel and turns up constantly. Cicero uses the word often; not at this rate.