From FTDNA Acker family website:
Although the name 'Acker' taken by itself is the German and Dutch word for 'field' (the English word 'acre' derives from the same root) thus suggesting a byname for 'farmer' or 'peasant', in actuality most variations of the surname in this country (the majority of which are German in origin)prove to be shortened (Americanized) versions of a name completely different in meaning and origin: namely, Eckhardt (or Eckert, as it is commonly spelled today).
In his dictionary of German Names, Hans Bahlow tells us that Eckhardt, which was a very popular name during the Middle Ages, comes from the Germanic Agihard which means 'bold with the sword' and is composed of the elements agi(n) ('point' or 'edge') and hard ('hardy', 'bold', 'brave', or 'strong') Some of the umpteen variations include Eckart, Eckehard, Eggehart, and Eggert, to name only a very few. The surname Einhart/Einert and its variants also derive from Agihard, as does the more unusual Edzard.
The name Ecker or Egger (without the final 't') which is often a short form of Eckhardt, can also mean 'from the dwelling place on the corner', from the root 'egg' or 'eck' meaning 'corner', and the ending -er which denotes an inhabitant. Note the similarity between roots agi (point or edge) and egg(e) (corner). 'Ackert', aside from being an Amercanized spelling of Eckert, can also come from the personal name Aquart(or the Old French Achart) which itself is a derivative of the Germanic Agihard.
Patronymic forms of the name (which typically end with 's' or 'son') must also be taken into consideration. Eggers means literally 'son of Eggert'. Ackerson and Eckerson are often shortened to Acker(s) or Ecker(s).
Thus, an entire spectrum of variations spring from the original root, and this project is intended to encompass the entire range.