Template:Ranksten

Ranks of Ten were used to organize many societies. Nimrod organized systems from the top down in tens. Free societies also organized themselves voluntarily sometimes called Tithingmen, Hundredsmen and Eoldermen which was also spelled Ealdormen which became which became the modern Alderman.
In the Latin Lexicon Numen from An Elementary Latin Dictionary by Charlton T. Lewis and A Latin Dictionary by Lewis & Short. We see:

decānus, decāni, m. decem.

1. "A chief of ten, one set over ten persons (late Lat.). Over soldiers, Veg. Mil. 2, 8." Also,
2. Over monks, a dean, Hier. Ep. 22, no. 35.
3. The chief of the corpse-bearers, Cod. Just. 1, 2, 4; 9.
4. As a judge, Vulg. Exod. 18, 21; Deut. 1, 15.
5. A kind of officer at the imperial court, Cod. 12, 27, 1.
   

Overtime time common usage creates a variety of associated terms:
A tithing could be called a decennary although that term could simply men ten years.
The chief of a tithing could be called a headborough particularly in Kent, Surrey and Sussex, but more commonly as a decener.
A decener (plural deceners) was historically "A soldier commanding ten men" or commonly called a tithingman who was the head of a tithing group of ten.
A ruler or leader of ten men was also called a decurion. We can see in Medieval Latin decennarius was a tithingman and was derived from decena, decenna which was a tithing (from Latin decem ten). In Latin all words can have numerous different suffixes depending on their use in a sentence like -us, -em,-it, -arius -ary etc..
The word decennis could also mean "of 10 years" depending on the context.
Even in Spanish the word decena means a set of ten but if you have a plural number of sets it would be decenas.
Also the word "dean" which can be spelled dene is from Middle English or the Old French deien which was from the late Latin decanus ‘chief of a group of ten’, from the Latin word decem again meaning meaning ‘ten’.
Even the proper name Dean is said to be derived from the Greek word "dekanos" ("δεκανός"), which means "monk or dignitary in charge of ten others", which was like the Latin "decanus" used in the Roman military to describe the head of a group of ten soldiers. In Classical Latin the letter "c" is pronounced k but in Church Latin "c" before e, i, y, ae, oe is pronounced ch but in all other cases, "c" is pronounced k. In the same way "cc" can be "tch" and similarly in Medieval.
While decanus should not be use interchangeably all the time with the Greek diákonos (διάκονος), from which the word deacon is derived it is reasonable to associate the terms because Christ commanded that his disciples organize the people in the tens, hundreds and thousands.