When confronted with linguistic analysis or diagramming of a sentence, linguists need to make decisions about part of speech. This is important when faced with assigning part of speech in a computational system as well. Not that it is always easy, mind you. Here is a little puzzle from French that makes it clear that words can mutate from one category to another.

The expression for 'need' in French is avoir besoin de, as in:

(1)	J'ai besoin de ce fichier.
	'I need that file.'

The lexical item besoin, as per the standard reference dictionaries in French, is a masculine noun. Classical syntactic tests show that it does in fact behave as a noun:

(2)	Manger est un besoin physiologique.
	'Eating is a physiological need.'
(3)	Il est dans le besoin.
	'He is in need.'
(4)	Le grand besoin des pays pauvres est indiscutable.
	'The great need of poor countries is indisputable.'

In each of these cases, the lexical item is modified by either an article or an adjective, or both. Since no other part of speech allows this behavior, we can agree with the dictionary that this is in fact a noun. Morphology also points to it being a noun, since it never inflects for gender.

However, when the word besoin is in the idiomatic expression avoir besoin, it displays both noun properties and adjectival properties. As a noun, it appears to be the direct object of the verb avoir but must appear without an article of any kind, i.e. in a bare noun form. It also allows a prepositional complement. On the other hand, it exhibits adjectival features such as modification by intensifying adverbs, superlatives and comparatives.

(5)	Il a bien besoin d'aide.
	'He really need help.'
(6)	Il en a le plus besoin.
	'He needs it the most.'
(7)	L'installation typique de Microsoft Office inclut les fichiers programmes dont vous aurez probablement le plus besoin pour effectuer votre travail.
	'Microsoft Office Typical installation includes the program files you're most likely to need to do your work.'
(8)	Il a plus besoin de la voiture que toi.
	'He needs the car more than you.'

The idiomatic besoin is one of a class of such expressions:

(9)	Cette terrible faim les tourmente.
	'They are tormented by this terrible hunger.'
(10)	Il a très faim.
	'He is very hungry.'

Examples in (11) through (15) show that the behavior of nouns like besoin and faim in the idiomatic context cannot be carried over to non-idiomatic use:

(11)	*	Besoin est clair.
		'Need is clear.'
(12)	*	Il a un bien besoin.
		'He has a real need.'
(13)	*	La très faim me tourmente.
		'Great hunger tourments him.'
(14)	*	Je remarque un plus besoin.
		'I notice a greater need.'
(15)	*	Je remarque le plus besoin.
		'I notice the greatest need.'

The phenomenon extends to other intensifier adverbs like extremement, absolument, etc.

(16)		Il a extrement faim.
		'He is extremely hungry.'
(17)	*	Il a une extremement faim.

Intensifier adverbs cannot modify nouns directly, nouns in French for the most part require determiners, and neither the comparative nor the superlative can directly modify a noun within a noun-phrase.

The problem seems to have only one solution. In the context of the idiomatic expression, the Noun is really an Adjective (read Adjective/Adverb), and thus accepts intensifying premodifiers reserved to adjectives. This makes them a form of syntactic chameleon, somehow mutating into another category when the environment dictates.

The context where one finds this behavior is broader than I have indicated so far. They appear to be part of a Verb Noun idiom, where this is indicated primarily by absence of an article on the Noun.

(18)	avoir besoin, avoir faim, avoir soif, avoir peur, avoir chaud, avoir froid, avoir envie, avoir raison
	'need, be hungry, be thirsty, be afraid, be hot, be cold, want, be right'
(19)	faire partie, faire envie
	'be part of, make (someone) want'
(20)	faire tache, prendre garde, n'avoir cure de, faire rage, faire signe
	'stain, take caution, not to worry about, let loose with fury, wave (?)'
(21)	faire montre, (se) rendre compte, faire reference, faire classe, rendre visite
	'show, realize, refer to, hold class, visit'
(22)	donner recours, passer commande
	'give recourse, order'

But not all have full chameleon properties. Those coupled with the verbs avoir and faire in (18) and (19) allow modification by an intensifying adverb (such as bien or très) and also allow comparative modifiers, and with the proper context, superlative modifiers. Those in (20)–(22), with apparent exceptions discussed below, do not.

(23)	Il rend (*bien/*très ) visite à sa sœur.
	'He visits his sister a lot.'
(24)	Il se rend (*bien/*très ) compte du problème.
	'He is very aware of the problem.'

Some of the idiomatic expressions in (20) to (22) appear to allow comparative and superlative premodifiers.

(25)	Nous nous rendons plus compte de ce problème que vous.
	'We realize the problem more than you.'
(26)	Nous rendons plus visite à notre mère que vous.
	'We visit our mother more than you.'
(27)	Nous rendons le plus visite le soir.
	'We visit most in the evening.'

But one quickly realizes that the comparative plus and the superlative le plus are independent adverbs, as they must float to intra-verb position when the sentence is put in a compound past tense.

(28)	*	Nous nous sommes rendus plus compte de ce problème que vous.
(29)		Nous nous sommes plus rendu compte de ce problème que vous.
(30)	*	Nous avons rendu plus visite à notre mère que vous.
(31)		Nous avons plus rendu visite à notre mère que vous.
(32)	*	Nous avons rendu le plus visite le soir.
(33)		Nous avons le plus rendu visite le soir.

The idioms in (18) and (19) however, allow both positions, as illustrated in (35)–(36) and (37)–(38):

(35)	L'installation typique de Microsoft Office inclut les fichiers programmes dont vous avez probablement eu le plus besoin pour effectuer votre travail.
(36)	L'installation typique de Microsoft Office inclut les fichiers programmes dont vous avez probablement le plus eu besoin pour effectuer votre travail.
(37)	Il a eu plus faim que vous.
	'He was hungrier than you.'
(38)	Il a plus eu faim que vous.

The superlative in (36) is in fact an independent verbal modifier, but the superlative in (35) cannot be. Similarly in (37), we must allow for the constituency of plus faim. One is forced to maintain the adjective interpretation for besoin and faim, as previously discussed. The conclusion that the idioms in (18) and (19) contain syntactic chameleons remains unchallenged.

The difference in the idiom behavior raises the possibility that we have a spectrum of change in front of us. At an earlier stage of the language, determiner use was freer; when determiners use became obligatory, a few idioms resisted the change. At the same time, use of the comparative and superlative within the adverbs caused the idiom to be reanalyzed into Verb Adjective. Of course, this is speculation, and would have to be verified on historical French data.

Endnote

^* Happy Birthday Jorge!! I wrote this up to remind myself of the days when you asked us to think of a squib a day. Thanks for being a charismatic teacher, inspiring linguist, and tireless volleyball player. [Back]