Wiktionary lists "fou" [1] as meaning "Crazy", which most likely comes from the French word "fou" [2] meaning "crazy".

The French word is said to come from the Old French "fol" [3] that means "mad, insane, foolish, silly". "Fol" is said to come from the Latin "follis" [4] which, based on wiktionary data, means "bellows", "purse, sack, money bag", etc.

None of the definition of "follis" seems to relate to crazy, foolish, mad or insane whatsoever. Therefore, what is the exact origin of "fou" in the sense of "crazy" OR how did it evolve from "follis" to "fou"?

[1] http://en.wiktionary.org/wiki/fou#English
[2] http://en.wiktionary.org/wiki/fou#French
[3] http://en.wiktionary.org/wiki/fol#Old_French
[4] http://en.wiktionary.org/wiki/follis#Latin

Edit 2018-07-14: The definition was wrong on Wiktionary from 2010 to 2013. As for the title question, the origin of the word "fou" is described in @Lambie's answer in more details.

  • Comments are not for extended discussion; this conversation has been moved to chat.
    – tchrist
    Commented Jul 15, 2018 at 20:51
  • So, after all that, you (the OP) were inspired to ask this question by reading the Wiktionary entry? In the end then the question isn't really what 'fou' means in English, but how did the French word 'fou' (crazy) come from Latin 'follis' ('bellows', 'bag'). Prety straightforward metaphor as others mentioned, a 'windbag' talks a lot, which may be drift into crazy. Also, it's a fairly common sound change to lenite (weaken) word final 'l', even to nothing.
    – Mitch
    Commented Jul 16, 2018 at 3:13

3 Answers 3


Of the Onelook results (excluding Wiktionary (and Worknik which just references Wiktionary)), all define it as "drunk"/"full" (like the OED).

As you only stumbled upon the word in Wiktionary and haven't seen it used for "crazy" in English, and as Wiktionary is editable by anyone, it may be a mistake, but it may also be a new English (loan-)word which isn't very common or widespread.

As it happens, Wiktionary's original English entry was for "Drunk" (28 August 2008). Someone without a username changed it to "Crazy" on 17 November 2010. There's no other edits recorded against their IP address, which as it happens resolves to Canada, a country whose official languages are English and French. My guess is either someone mixed up the French and the English words, or that some people in Canada really do use the word fou to mean "crazy". However, I don't expect this is very widespread, and most other speakers of English won't recognise it (meaning either "crazy," "drunk" or "full"), so I'd advise not to use the word in English.

  • 1
    This is a Scottish word.
    – Lambie
    Commented Jul 12, 2018 at 13:39
  • en.oxforddictionaries.com/definition/fou Scottish Inebriated; drunk. ‘his lordship gets them fou, steamin' fou’ [short for foul]
    – Lambie
    Commented Jul 13, 2018 at 18:40
  • Indeed. The Scottish drunk/intoxicated is the only definition in the OED, going back to 1535 in English (D. Lindsay Satyre 139 Na he is wod drunkin I trow; Se ȝe not that he is wod fow?) , from a Scots variant of full. The question was asked when there was an unreliable on Wiktionary which it is good to see has now been fixed.
    – Hugo
    Commented Jul 14, 2018 at 16:31
  • Thank you for that acknowledgment. I do deserve some credit even though I did not realized the time frame initially. The OP is asking about etymologies and the two derivations are 100% different. I received two downvotes...people are nuts around here. :)
    – Lambie
    Commented Jul 14, 2018 at 16:35

In tracing the etymological development of fou and thinking about English derivitives, we are given the following information in the OED entry for fool: Forms: ME fol, (ME folle), ME–15 fole, (ME foyl), ME–15 foule(e, (ME fowle), ME–16 foole, (15 foolle), ME–18 Sc. fule, ME–15 full(e, ME–16 Sc. fuil(l, -yll, (ME fwle), ME– fool, 15 south. vool, 15 Sc. fuyl. Etymology: Middle English fōl noun and adjective, < Old French fol noun and adjective (modern French fou noun, insane person, madman, fou adjective masculine, before vowel fol, feminine folle), corresponding to Provençal fol, folh, Italian folle < Latin follem, follis, lit. ‘bellows,’ but in late popular Latin employed in the sense of ‘windbag,’ empty-headed person, fool.

  • The word fou in Scottish is from the word foul. Your derivation chain is off for this meaning.
    – Lambie
    Commented Jul 12, 2018 at 13:53

This is a Scottish term but its first meaning is like the English word full:

Wiktionary entry:

English Adjective fou (comparative more fou, superlative most fou)

(Scotland) Drunk.

The definition below is from the Dictionary of the Scots Language. It is authoritative and definitive. (Downvote at your own risk.)

"Introduction The Dictionary of the Scots Language (DSL) comprises electronic versions of the two major historical dictionaries of the Scots language: the 12-volume Dictionary of the Older Scottish Tongue (DOST) and the 10-volume Scottish National Dictionary (SND) with its two supplements (1976 and 2005)."

FOU, adj., adv., n., v. Also fu', foo(e), †foue, †fow(e); †foul. Sc. forms and usages of Eng. full. See P.L.D. § 78 (3) and Full. [Sc. fu:; s.Sc. fʌu]

There is an entire page of quotations, variations and citations.

I. adj. 1. As in Eng. Edb. 1720 A. Pennecuik Helicon 78: His Face was big and fair like a fow Moon.


  1. Full of food, well-fed, sated, replete (ne.Sc., Ags., Fif., m.Lth., Bwk., Rxb. 1953). Also fig.

  2. Full of liquor, drunk, intoxicated. Gen.Sc. Used also with bitch, blin, greetin, roarin, stottin, tumblin, etc. to indicate the degree or nature of the intoxication, and in many similes as fou as a buckie, a piper, a puggie, a wilk, the Baltic, the ee o' a pick (see Ee, n., 2. (2)), etc., etc., in some of which fou partly retains its meaning 1. Deriv. fouish, slightly drunk, tipsy (Edb. 1828 D. M. Moir Mansie Wauch (1898) ii.).

‡4. In comfortable circumstances, well-off, having plenty, well-provided (Rxb. 1923 Watson W.-B.); bountiful, open. Deriv. †fowie, id., gen. used with contemptuous force, implying miserliness (Rxb. 1825 Jam.).

  1. Combs.: (1) fou-han't (Cld. 1880 Jam.), -hannit (Bnff. 1866 Gregor D. Bnff. 224; Abd.27 1953), having the hands full, having a sufficiency; fully repaid or requited; (2) fou-hauden, -hadden, lavishly supplied, having no lack or scarcity, esp. of food (Rxb. 1923 Watson W.-B.); (3) fou-moot, having all the teeth in a sound state (Bnff. 1866 Gregor D. Bnff. 224). Eng. has full-mouthed, id., of cattle.

‡II. adv. Fully, very, quite; rather, too; with compar., much (Per., Fif., Lth., Ayr. 1915–26 Wilson; Ork., Cai., Abd., wm.Sc. 1953). Now arch. or dial. in Eng.

III. n. 1. A fill, the quantity that fills, the full capacity (Gall. 1824 MacTaggart Gallov. Encycl. 209; Sh., Cai., ne.Sc., Ags., Fif., Clc., Gall., Dmf., Uls. 1953), a full load; specif. of drink, as much as one can hold.

†2. In dry measure: a firlot or quarter boll, approx. = one imperial bushel of wheat or 1.4 of a bushel of barley or oats; “the full of a measure of potatoes, onions, etc. . . . This is always supposed to be heaped unless the term sleek be used, which is equivalent to straik or stroke” (Cld., s.Sc. 1825 Jam.); a vessel holding this amount. Also foul (Ayr. 1706 Arch. and Hist. Coll. Ayr. and Wgt. IV. 216). Cf. Full, n. 2., and half-fou, s.v. Half, adj., 1.

‡IV. v. To fill (Abd. 1825 Jam.), to load. Redupl. form foo-foo. Gsw. 1877 A. G. Murdoch Laird's Lykewake 71: Think o' yer wark! the greedy laird's foo-fooin' up the purse.

Fou is a variant form of the word foul in Scottish, which means unwashed or dirty:



  • Given the possible derivations of 'fou', we don't know what the OP is actually referring to without a sentence of context. It could be from the Scottish variant of 'full' or it could be from French for 'crazy'. Dictionary.com has both. But OED only has the Scottish. I would tend to trust the OED first, then dictionary.com, and only then wiktionary. My tenuous judgement is that the OP saw a French 'fou' out of place or made a mistake in assuming it was French.
    – Mitch
    Commented Jul 14, 2018 at 21:26
  • The pronunciations of 'fou' at these different sites, not knowing how Scottish normally pronounces such orthography, is suspect. If from French I would expect /fu:/, which is what all the sites give. If from Scottish I'd expect something like /faw/ (rhymes with 'cow') in oder to be a shortening of 'foul', which none of these sites give. But maybe Scottish pronounces the shortening of foul, "fou' ", like /fu:/. I don't know
    – Mitch
    Commented Jul 14, 2018 at 21:28
  • Mitch, in English, it's from Scottish English, I have no idea about the pronunciation but am sure of the meaning. The OED only has the Scottish because the French word is not related to the Scottish one at all. There had been a mistake in Wiktionary.
    – Lambie
    Commented Jul 14, 2018 at 23:16