Where it sits
Listed in the dictionary, common in speech and ads, still rejected by most usage panellists for formal writing.
What it doesn't mean
Merriam-Webster's entry for the adjective fun gives 'sometimes funner; sometimes funnest', and its FAQ answers 'Is funnest a word?' with a plain yes.
Not a rule, a habit. Short adjectives normally take -er and -est (big, bigger, biggest). The resistance comes from fun's history as a noun, and from the forms sounding childish to many ears.
What it really means
Funnest sounds like something a six-year-old made up. It isn't, quite. It's what happens when the grammar of English catches up with how people use a word.
Start with fun. Since the 1700s it has been, above all, a noun: you have fun, you do things for fun. Etymonline dates its use as an adjective meaning "enjoyable" to 1846. American Heritage suggests how it happened: people heard "skiing is fun" and took fun as an adjective, like "skiing is enjoyable". From there it was a short step to "a fun time".
That adjective is now standard. In American Heritage's 2015 survey, 84 percent of its Usage Panel accepted "we went to a fun party".
Ordinary short adjectives take -er and -est: big, bigger, biggest. So once fun behaved like an adjective, funner and funnest followed. American Heritage dates them to the 1950s.
Here the dictionaries part ways a little. As checked in October 2026, Merriam-Webster lists them directly, giving the adjective as "sometimes funner; sometimes funnest", and answers its own FAQ "Is funnest a word?" with yes. American Heritage is cooler: the forms are almost never found in edited prose except in quotations, usually of children, and its panel rejected funner (88 percent) and funnest (80 percent).
So it's a real word with an informal flavour. Use more fun and the most fun in an essay, a report or a speech you want taken seriously. In a text, an ad, or a sentence about the best birthday ever, funnest is fine.
Where it comes from
English — noun from the 1700s; adjective 'enjoyable' from 1846 (Etymonline)
English — the ordinary superlative ending, as in fastest, kindest
The ending is perfectly regular. The objection is to the stem: for many speakers fun is still really a noun, and nouns don't take -er and -est.
- 1846
Etymonline's first date for fun as an adjective meaning 'enjoyable'.
- 1950s
American Heritage dates the inflected forms funner and funnest to this decade.
- 2015
84 percent of American Heritage's Usage Panel accept 'we went to a fun party'.
- Today
American Heritage reports its panel rejects funner (88 percent) and funnest (80 percent).
In real life
- "Best. Day. Ever," said the six-year-old. "This is the funnest party in the whole world."
- The ad promised 'the funnest family day out', and the copy editor let it go because it was an ad.
- Is the new version funner than the original? The reviews say yes, and also that it has fewer bugs.
Questions
Q01Is funnest a real word?
Yes. Merriam-Webster lists funner and funnest as forms of the adjective fun and says both have been widely used for decades. They are informal, though: American Heritage notes they are almost never found in edited prose except in quotations.
Q02Should I say more fun or funner?
In formal or careful writing, use 'more fun' and 'the most fun'. In speech, texts or playful copy, funner and funnest are common and understood by everyone.
Q03Why do people object to funner and funnest?
Because fun started as a noun ('we had fun'). Its adjective use ('a fun party') arrived later and is now standard; Etymonline dates it to 1846. Adding -er and -est treats it like an ordinary adjective, which some readers still resist.
Q04How many usage experts accept funnest?
Few. In American Heritage's Usage Panel survey, 80 percent of its Usage Panel rated funnest unacceptable and 88 percent rejected funner; most of the rest rated them only 'somewhat acceptable'.
Sources
- fun — Merriam-Webster (entry and FAQ: 'Is funnest a word?').
- fun — The American Heritage Dictionary (usage note).
- fun — Online Etymology Dictionary.