Aside from the self-reference discussed below, the English language has three one-letter words:

• a – the indefinite article
• I – the first person singular nominative pronoun
• O – an interjection derived from the vocative case of Latin, commonly used in poetry

Both I and O are capitalized when used.

The word E is the shortest English neologism and is a Spivak pronoun meaning he or she. It, along with X, is also a common abbreviation for the drug Ecstasy.

e is a mathematical and scientific constant, referring to the base of the natural logarithm. Many other such constants also have single-letter symbols, suchs as c.

In gangster rap culture, G is a valid word, a contraction of "gangster", used as a term of respect.

There are also various single letter words used as abbreviations in text-speak and related uses:

• b – "be"
• c – "see"
• f – "fuck", often a euphemism
• g – "Gee"
• k – "okay"
• n – "and"
• o – "oh"
• p – "pee" (urination)
• q – "queue"
• r – "are"
• t – "tea"
• u – "you"
• v – "very", for example: V Graham Norton
• y – "why"

Various digits have also been pressed into service in this manner:

• 2 – "to", "too". Can also be used as part of a word. E.g. 2moro (tomorrow).
• 4 – "for" – Can also be used as part of a word. E.g. 4cast (forecast), 4t (thought).
• 8 – "ate" – Can also be used as part of a word. E.g. l8r (later), complic8 (complicate).
• 9 – "night", a shortened form of "good night"

Self-reference: Every letter is a word

Large dictionaries list each letter as a single-letter word. Each such word is defined as a noun, denoting the letter with which it is spelled. This blurs the use-mention distinction: one can write

"Psychology" starts with a "p".

mentioning the letter p, or one can write

"Psychology" starts with a p.

using the word p.

These nouns often form the plural irregularly, with an apostrophe:

"Egg" has two g's.

See also

• Longest word in the English language
• Two-letter English word