Like English, Sindarin has a definite article i “the”, but unlike English it has no indefinite article “a, an”. In Sindarin, an indefinite item is specified by the bare noun: “the man” = i adan but “a man” = adan. The definite article is effectively a proclitic, closely associated with the following word, and as a result causes soft mutation. The definite article also has a plural form in which causes nasal mutation. This proclitic nature and mutational features of the Sindarin article were described by Tolkien in various places for both Sindarin and its conceptual precursors such as Noldorin:

i, article “the”, indeclinable as a rule in Quenya. In Sindarin it shows inflexions, exhibited mainly in effect on initial consonants, as perian = “halfling”, i berian “the halfling"; i pheriain, pheriannath “the halflings” (from a draft for a 1955 letter to David Masson, PE17/66).

In pronominal words m was used often for the indication of plurality. In Noldorin this survived notably in ī̆m, the plural of the deictic particle or article. This became in, but the nasal was not lost since the article became proclitic and closely associated with the following word. Thus ON inatari, intali, iñkhoni (Common Eldarin: Noun Structure, early 1950s, PE21/77).

The historical origin of the definite article is described in The Etymologies of the 1930s:

I- “that” (deictic particle) in Q is indeclinable article “the”. N i- “the”. plural in or i- (Ety/I¹).

As a marker of its proclitic nature, Tolkien would sometimes (but not always) use a dash (-) or a dot (·) between the article and its noun, as in: ónen i-Estel Edain “I gave [the] Hope to the Dúnedain” (LotR/1061); i·Veleglind “*the Great Song” (VT50/5).

Some examples of the use of singular (i) and plural (in) articles include:

• Singular i:
  • Before a vowel: i arben “the knight” (PE17/147).
  • Soft mutation b → v: i Varanduiniant “the Bridge (iant) of Baranduin” (SD/129).
  • Soft mutation h → ch: i Cherdir “the master (herdir)” (SD/129).
• Plural in:
  • Before a vowel: in Ellath “the Elves” (VT50/5).
  • Nasal mutation p → ph: i Pheriannath “the Halflings (Periannath-class-plural)” (LotR/807).
  • Nasal mutation t → th: i thiw “the signs (têw-plural)” (LotR/305; PE17/40).
  • Nasal mutation s → s: i Sedryn “the Faithful (sadron-plural)” (UT/153), vs. soft mutation s → h.

As shown by the examples above, the full plural article in is seen before vowels, but the n is lost before (most) consonants, with nasal mutation being the only sign of its nasal nature. The plural article is used for both regular plurals (sedryn) and class plurals (Ellath). The more complete rules for soft mutation and nasal mutation are discussed in their own entries.

Compared to English, Sindarin uses the definite article less frequently. Tolkien noted the less frequent use of the article in the Early Noldorin Grammar of the 1920s:

The definite article (sparingly used and never generically) is: i sg. causing soft mutation of initial consonant; i(n) pl. causing nasal mutation of initial consonant (PE13/120).

This statement gives one indication of a circumstance where Sindarin would not use an article. English allows the definite article to be used “generically” even when not referring to a specific thing, as in: “the sword is an important tool for a warrior”. Apparently Sindarin cannot do this, and would say megil *carf *vall am maethor (*carf “tool” and *ball “important” are neologisms).

There is some indication that, like Quenya, a genitive or possessive expression defines the preceding noun, so that no article is required. Only rarely do such expressions have a preceding article in Sindarin, as in:

• alae! ered en Echoriath, ered e·mbar nín “behold! the mountains of Echoriath, the mountains of my home!” (UT/40).
• Ennyn Durin Aran Moria “the Doors of Durin, Lord of Moria” (LotR/305).
• glim maewion “(the) voices of gulls” (PE17/97).
• Narn e·Dant Gondolin ar Orthad en·Êl “*Tale of the Fall of Gondolin and the Rising of the Star” (MR/373).
• o menel aglar elenath “from heaven ... the glory of the starry host” (RGEO/63).
• roch na-heryna “the horse of (the) Lady” (PE17/97).

There are a number of exceptions, however:

• i chîn Húrin “the children of Húrin” (VT50/5).
• i·m(b)air en N(d)engin “the houses of the Slain” (PE17/97).
• i·arben na megil and “Knight of the Long Sword” (PE17/147).

One circumstance where Sindarin does use a definite article even though English does not is with possessive pronouns. Such pronouns are functionally adjectives and appear after the noun, which also has a preceding article, as in:

• i eneth lín “thy (lín) name” (VT44/21).
• i arnad lín “thy (lín) kingdom” (VT44/21).
• i mbas ilaurui vín “our (mín) daily bread (bas)” (VT44/21).
• i úgerth vin “our (mín) trespasses (úgerth)” (VT44/21) [sic., in would normally be expected before a plural noun].

In English, the possessive pronoun precedes the noun and fills the “determiner slot”, but in Sindarin the pronoun follows the noun and so a definite article is still required. This is similar to how Welsh manages possessive pronouns. There are, however, attested exceptions to this as well: ionnath dîn “his sons” and sellath dîn “his daughters” appear without the definite article in the King’s Letter (SD/129); perhaps it is significant that these are class plurals, or that they follow a set of personal names.

Conceptual Development: The singular and plural forms of the definite article date all the way back to the Early Noldorin Grammar of the 1920s, where they caused soft and nasal mutations respectively (PE13/120). However, in the Gnomish of the 1910s, the form in was not specifically plural, but was rather the form used before vowels. The simple article i was both singular and plural in Gnomish, and caused soft mutation in all circumstances:

i- proclitic, causing softening of initial consonant. in- before vowel ... definite article “the” (Gnomish Lexicon, GL/50).

Nominative singular and plural i· followed by “interior changes”: i.e. c gave ·g, cr gave ·gr [etc.] (Gnomish Grammar, GG/7).

Hence G. i·winin na gwandron “[the] women (gwin-plural) are beautiful” (GG/9) had soft mutation instead of nasal mutation, and for this reason nasal mutation did not become a feature of the language until a later conceptual stage.