Two-letter words that contain a Z include "Oz," as well as "za" and "zo," both of which are acceptable in Scrabble games. There are no two-letter words that include a V.
The letters V and Z are two of the rarest letters in the English language, appearing in approximately 0.978% and 0.074% of words, respectively. In terms of frequency of letters at the beginnings of English words, V and Z start off 0.649% and 0.034%.
The letters V and Z are just as rare in other languages. For example, in French, letter V appears in 1.838% of words, while Z appears in 0.326% of words. In German, V starts 0.846% of words and Z starts 1.134% of words. In Spanish, V is a letter in only 1.138% of words, while Z is a letter in 0.467% of words.
In ordering the letters of the English alphabet, Z is considered the least common letter, while V is considered the fourth least common letter.
Project Gutenberg has found that the letters are not only uncommon, but they also are not part of any common bigrams or trigrams. This means that they do not frequently appear in sequences of two- or three-letter words.