This is the 4207th most frequent French word.
duquel
"Duquel" means "of which" or "of whom" in English and is a masculine singular form used in formal or complex sentences.
"Duquel" is used as a relative pronoun combining "de" (a preposition) and "lequel" (a pronoun), to refer to a specific antecedent, "le livre".
Le livre duquel j'ai parlé est sur la table.
The book I talked about is on the table.
"Duquel" serves to introduce a relative clause, replacing "de" + "lequel", connecting the noun "le dossier" to the action described.
Voici le dossier duquel nous avons extrait les informations.
Here is the file from which we extracted the information.
"Duquel" is used to show possession or relation to "un sujet", indicating the association between "savoir presque rien" and "un sujet".