From Tolkien Gateway

i (plural in in Sindarin) is the Quenya and Sindarin article "the" and relative pronoun "who".

Sindarin[edit | edit source]

Mutations[edit | edit source]

In Sindarin, the singular form causes lenition to the following word. For example tâl "foot" > i dâl "the foot".[1]

The plural form causes nasal mutation, and the final -n is assimilated. For example Periain "Halflings" > in+Periain > i-Pheriain "the Halflings".[2]

(The affection is usually noted with a hyphen or a dot between article and word.)

Related forms[edit | edit source]

These Sindarin prepositions contain the suffixed article -in:

The above combined articles when before a word, cause a peculiar phenomenon of lenition different from the above.[3]

As a relative pronoun[edit | edit source]

In both Quenya and Sindarin, i is used for the relative pronoun "who" or a conjunction "that", introducing a secondary phrase. In Quenya it is usually the plural form of ya/ye but can also be used in the Singular.

For example:

In Quenya, it can also be declined as a noun: