The indefinite relative pronouns ce dont and quoi are used when replacing the indirect object of a preposition.
The indefinite relative pronouns ce que and ce qui both mean "what" or "that."
Indefinite adjectives like certains, divers, and quelques describe nouns in a general or non-specific way. Many indefinite adjectives indicate a vague quantity.
The aptly named indefinite article (un, une, des) indicates an unspecific or unidentified countable noun.
Indefinite demonstrative pronouns (ce, ceci, cela, ça) do not agree with the nouns they replace in gender or number.
Indefinite relative pronouns (ce dont, ce que, ce qui, ce à quoi) are connectors: they link relative clauses to main clauses and, unlike normal relative pronouns, do not not have a specific antecedent.
The indefinite French subject pronoun on literally means "one," but is usually translated by an indefinite subject. Agreement with the subject implied by on is optional - at least in theory.
The third person indefinite stressed pronoun soi doesn't have a straightforward English equivalent, so French students often confuse it with lui.
The subjunctive is required after any type of construction that indicates negativity or doubt, including negative pronouns and indefinite pronouns.