How do you write FAT in greek?

There isn't a direct, single-word translation of "FAT" into Greek that captures all its meanings. The best translation depends heavily on the context:

* If "FAT" refers to body fat: Λίπος (lípos) is the most common word for fat in this context.

* If "FAT" refers to a file allocation table (in computing): Πίνακας κατανομής αρχείων (Pínakas katatomís archeíon) would be a literal translation, but Πίνακας αρχείων (Pínakas archeíon) - "File table" - might be more easily understood. You could also use the English acronym FAT, as it's widely understood in technical contexts.

* If "FAT" is an acronym in a different context: You would need to translate the full words that the acronym represents.

Therefore, you need to provide the context of "FAT" to get the most accurate Greek translation.