Litla stelpan skríður undir borðið.

Because litla stelpan means the little girl, while litil stelpa means a little girl.

In Icelandic, both the adjective and the noun change form depending on things like:

• gender
• number
• case
• whether the noun is definite (the) or indefinite (a)

Here:

• stelpan = the girl
• because the noun is definite, the adjective takes the weak form
• the weak feminine nominative singular form of lítill (little/small) is litla

So:

• litil stelpa = a little girl
• litla stelpan = the little girl

Also note that the dictionary form of the adjective is usually lítill, but in actual sentences it changes a lot.

In Icelandic, the definite article (the) is usually attached to the end of the noun instead of standing as a separate word.

So:

• stelpa = girl
• stelpan = the girl

That final -n is the definite article here.

This is very common in Icelandic:

• hestur = horse
• hesturinn = the horse
• borð = table
• borðið = the table

So Icelandic often expresses the as a suffix rather than a separate word like English does.

Borðið is the definite form of borð, which means table.

So:

• borð = table
• borðið = the table

The noun borð is neuter, and in this sentence it appears with the definite article attached.

A useful thing to notice is that for many neuter nouns, the nominative and accusative singular forms are the same. So borðið can be both:

• the table as a subject
• the table as an object or destination, depending on the sentence

Here it is not the subject; it is part of the prepositional phrase undir borðið.

This is a very common Icelandic question because some prepositions can take different cases depending on meaning.

Undir can take:

• accusative when there is movement toward a place
• dative when there is location in a place with no movement

In this sentence, the girl is crawling under the table as a movement toward that position, so Icelandic uses the accusative:

• undir borðið = under the table (motion into/under)

Compare:

• Litla stelpan er undir borðinu. = The little girl is under the table.
  
  • Here there is no movement, just location, so dative is used: borðinu

So the difference is:

• undir borðið = moving under it
• undir borðinu = being under it

Skríður is the 3rd person singular present tense of the verb skríða, which means to crawl.

So:

• að skríða = to crawl
• ég skríð = I crawl
• þú skríður = you crawl
• hann / hún / það skríður = he / she / it crawls

In this sentence, the subject is litla stelpan (the little girl), which is 3rd person singular, so the verb form is skríður.

Because Icelandic, like English, often uses subject + verb order in a basic statement.

So the structure here is:

• Litla stelpan = subject
• skríður = verb
• undir borðið = prepositional phrase

That gives:

• The little girl
  • crawls/is crawling
    • under the table

This is a normal, straightforward word order in Icelandic.

It can mean either, depending on context.

Icelandic simple present often covers both:

• crawls
• is crawling

So Litla stelpan skríður undir borðið could be understood as:

• The little girl crawls under the table
• The little girl is crawling under the table

In many everyday contexts, English would prefer is crawling, but Icelandic does not need a separate present progressive form the way English often does.

Because that is the normal position for most descriptive adjectives in Icelandic.

So:

• litla stelpan = the little girl

This works much like English:

• the little girl
• the big house
• the red car

The important difference is not the position, but the fact that Icelandic adjectives change form to match the noun.

Here litla agrees with stelpan in:

• gender: feminine
• number: singular
• case: nominative
• definiteness: definite/weak form

It is nominative singular feminine.

That is because litla stelpan is the subject of the sentence, and subjects are usually in the nominative case.

So:

• stelpan is nominative singular definite
• litla matches it in the nominative singular feminine weak form

This agreement between adjective and noun is a key feature of Icelandic grammar.

The dictionary form is lítill.

This is one of those Icelandic adjectives that changes quite a bit:

• lítill = masculine nominative singular
• lítil = feminine nominative singular, usually indefinite
• lítið = neuter nominative singular
• litla = weak form used here with a definite feminine noun

So even though you see litla in the sentence, you would normally look up lítill in a dictionary.

You usually learn the gender as part of the noun.

In Icelandic, every noun has grammatical gender, and that affects:

• adjective forms
• article forms
• pronouns
• sometimes verb-related patterns in larger constructions

Here:

• stelpa is feminine
• borð is neuter

You often need to memorize noun gender when learning vocabulary. Over time, you will also notice some common patterns, but there are many exceptions, so it is safest to learn each noun together with its gender and a definite form if possible.

For example, it helps to learn:

• stelpa – stelpan
• borð – borðið

rather than just the bare noun alone.