Bark

Baruk is a Khuzdul word which means "axes". The corresponding singular is bark. It's another example "broken plurals" in Khuzdul, similar to "khuzd" and "khazâd".

It's possible that "baruk" is actually a genitive case, meaning "axes of <something>" rather than just "axes". The phrase "baruk Khazâd" can be compared to a "construct pair" in Semitic languages, such as Hebrew and Arabic.