Tout à l'heure

In this expression, "tout" and "à l'heure" are both adverbs, so there's no agreement. (Adverbs normally don't agree, but there's an odd rule with the adverb "tout" that means it agrees with a feminine adjective beginning with a consonant or aspirated h, e.g. "elle est toute contente", but this never happens when it's followed by an adverb.)

Actually, when I think about it, "à l'heure" can also be an adjectival phrase, but although heure is feminine, the phrase doesn't really have a gender. Also it begins with a vowel, so it wouldn't be covered by that odd rule.

There are different ways to use tout in French - as a pronoun or an adjective - to express slightly different things:

Tout  =  everythingTout m'ennuie.Everything bores me.Je comprends tout.I understand everything.Used on its own, the invariable pronoun tout means everything.

 

Tout/tous/toute/toutes [chose(s)] = All [things] / the whole [thing(s)]Toute la journée, mon chat dort.
All (of the) day/ the whole day long, my cat sleeps.J'ai mangé tout le gâteau.I ate all the cake. / I ate the whole cake.Toutes mes soeurs sont très énervantes!All my sisters are really annoying!Je trouve tous les pays intéressants.I find all countries interesting.

To say all (the) [things] or the whole [thing], you will use the adjective tout, as follows :

tout/tous/toute/toutes + article + noun

Note that as an adjective, tout agrees in gender and number with the thing it refers to, as such:

 MasculineFeminineSingular   tout
toute
Pluraltous
toutes
In this case, tous is always pronounced [too]: the -s is silent.
Tous / toutes  = all [of them]Used on their own, pronouns tous or toutes replace prementioned nouns.
As such, tous/toutes agrees in gender with the thing they're replacing (it always expresses a plural quantity!).

Tous/toutes can be used either as:

- the subject of the verb = All [of them] did that.Les garçons ont passé leur examen et tous l'ont eu.
The boys took their exams and all of them passed .On regardait les lucioles, et soudain toutes ont disparu.We were watching the fireflies, and suddenly all of them disappeared.Mes amis sont venus et tous étaient contents.My friends came and all were happy.- a complement to the existing plural subject = They all did that. Mes amis sont venus et ils étaient tous contents.My friends came and they were all happy.Les garçons ont passé leur examen et ils l'ont tous eu.The boys took their exams and they all passed .On regardait les lucioles, et soudain elles ont toutes disparu.We were watching the fireflies, and suddenly they all disappeared.In this last case, tous/toutes is placed after the verb in simple tenses, or between the auxiliary and the past participle in complex tenses.In this case, tous is always pronounced [toos], to differenciate it from tout (everything)!

 

Pronunciation guide

Tout (masc. sg.) => [too]

Tous (masc. pl.) => [too] or [toos] depending on usage: see above.

Toute (fem. sg.) => [toot]

Toutes (fem. pl.) => [toot] (the -s is always silent, even when followed by a vowel: NO liaison!)