What is the meaning of -inn?

marks definiteness of a noun; the

synthetic first person singular past habitual tense ending in the first conjugation

synthetic first person singular past subjunctive ending in the first conjugation

used to create adjectives from nouns, meaning "made from"

used to create adjectives from verbs, meaning "prone to"

 denotes the past participle form of a strong verb

the

There must be agreement between the suffix and the noun, in gender, case and number.

The suffixed article will lose its -i- after the short closing vowels -a, -i, and -u. Note that, usually, contraction will happens also after a long closing vowel, but not if it leaves the word monosyllabic.

In the plural, the suffixed article will lose its -i- after -r.

In the dative plural, the suffixed article will lose its -i-, and the noun will lose its final -m.

Source: wiktionary.org