Questions & Answers about Miksi suusi on vihreä?
How does the word suusi mean "your mouth"?
The base word for "mouth" is suu. To say "your" in standard written Finnish, you attach the second-person singular possessive suffix -si directly to the end of the noun, creating suusi.
Shouldn't it be sinun suusi to include the word for "your"?
In standard written Finnish, you can safely drop the pronoun sinun (your) because the suffix -si already makes it perfectly clear whose mouth it is. Saying sinun suusi is also correct, but using just suusi is very natural.
Why doesn't the adjective vihreä (green) get a -si ending too?
Possessive suffixes like -si are only attached to nouns (the thing being owned) or sometimes to postpositions. Adjectives that describe the noun do not take possessive endings, so vihreä stays exactly as it is.
Since this sentence is about "you" (your mouth), why is the verb on (is) instead of olet (you are)?
The subject of the sentence is the mouth (suu), which is an "it" rather than a "you". Because of this, the verb needs to be in the third-person singular form on (it is). This works just like English, where we say "your mouth is".