Learn Hardcore Turkish: Masanın altını temizliyorum.

masanın is masa (table) plus the genitive suffix -nın (harmonized as -ın). It means “of the table” or “the table’s,” marking masa as the possessor.

Why does altını have two suffixes, and what are they?

altını breaks down as:
• alt (underside)
• -ı (3rd person singular possessive, “its underside,” yielding altı)
• -nı (accusative, definite object marker, harmonized as -nı)
Together, altını means “the underside of it” and marks that specific underside as the direct object.

Why do we need the accusative suffix on altını?

In Turkish, a definite direct object takes the accusative suffix -nı (here written -ını). It shows you are cleaning that particular underside. Without it, masanın altı temizliyorum would be ungrammatical or sound like you’re just mentioning the underside.

How is temizliyorum formed?

temizliyorum =
• temizle- (root “to clean”)
• -iyor (present continuous tense suffix)
• -um (1st person singular ending)
Vowel harmony changes -iyor + um into -iyorum, so you get “I am cleaning.”

Why is there no subject pronoun for “I” in this sentence?

Turkish verbs carry person information in their endings. The -um in temizliyorum already means “I,” so the pronoun ben (“I”) is usually omitted unless you want to emphasize it.

Why don’t we use an article like “the” or “a” in Turkish?

Turkish has no articles. Definiteness is conveyed by context and case marking. Here, the accusative suffix on altını signals that it’s a specific underside (“the underside”).

Could we instead say masanın altına temizliyorum or masanın altında temizliyorum?

Those forms use the locative (-da) or dative (-a) cases:
• masanın altına temizliyorum = “I am cleaning toward/under the table” (not natural for cleaning)
• masanın altında temizlik yapıyorum = “I am doing cleaning under the table” (focuses on location of the cleaner, not the table’s underside)
To express “I’m cleaning the table’s underside,” you need the direct-object construction masanın altını temizliyorum.