In Klingon, relative clauses describe a noun using a verb ending in the Type 9 suffix -bogh. These clauses translate English phrases like “the man who is running,” “the dog that we saw,” or “the bomb which exploded.” The noun being described is called the head noun.

The position of the head noun (before or after the relative clause) depends on whether it acts as the subject or the object of the clause. Subjects come after the verb; objects come before it.

• qIppu'bogh yaS – the officer who hit him/her
  (yaS is the subject, so it comes after the verb)
• yaS qIppu'bogh – the officer whom he/she hit
  (yaS is the object, so it comes before the verb)

The entire relative clause plus its head noun acts like a regular noun in a sentence:

• qIppu'bogh yaS vIlegh – I see the officer who hit him/her.
• mulegh qIppu'bogh yaS – The officer who hit him/her sees me.
• yaS qIppu'bogh vIlegh – I see the officer whom he/she hit.
• mulegh yaS qIppu'bogh – The officer whom he/she hit sees me.

In English, we often drop the word “who” or “that.” In Klingon, -bogh is required and cannot be omitted.

Basic Sentence Building with -bogh

Start with a simple sentence:

• qet loD – A man runs.

Turn it into a relative clause by adding -bogh to the verb:

• qetbogh loD – A man who is running / a running man

This phrase can be used in a larger sentence:

• HoH qetbogh loD – A man who is running kills.
• qetbogh loD HoH – He/she kills a man who is running.

If the relative clause includes another noun, use -'e' on the head noun to show which noun is being described:

• loD HIvbogh be'''e' – the woman who attacks the man
• loD'e' HIvbogh be' – the man who is attacked by the woman

You can also describe things like "a man in a coat" with a relative clause:

• wep tuQbogh loD'e' – the man who is wearing a coat

The head noun of a relative clause can only be the subject or the object of that clause. More complex roles require breaking the sentence into multiple parts, so for a sentence like "the ship on which the captain kills the prisoners is very large" the translation would be two sentences "Duj tInqu'. DujDaq qama'pu' HoH HoD." – The ship is very big. The captain killed the prisoners on it.

There are some situations where ambiguity is unavoidedable. For example:

• DujDaq puq DaqIppu'bogh vIlegh – I see the child who you hit on the ship, or, On the ship, I see the child you hit.

Both meanings are valid depending on context—just like in English.