Decebal

Decebal was not the real name of the king (his real name was Diurpaneus). Decebal was only a nickname meaning "the brave", "the strong".
[noted -ed]

"Decebal" is a kind of construction for "he is able to kill ten" in the Dacian language (dece-, as you can see, is a old Indo-European root for "ten" like "decem" in Latin).

The name Decebal is composed by two words: "Dece" with the meaning: "Daci"-(ancient tribe) and "Bal/balus" an Indo-European word meaning: "the power of".
The original name of king Decebal was Diurpaneus.