"Basal State" is a term used for coins that are of the lowest grade.

A Basal State coin is "identifiable and unmutilated, but so badly worn that only a portion of the legend or inscription is legible," according to William H. Sheldon, whose book Penny Whimsy was quoted by editor Steve Roach in a 2013 Coin World article.

Sheldon, who introduced the term, says that enough of the coin must remain for variety identification to be considered Basal State.

Basal State is used as a substitue for the term "Poor" in coin grading. Sheldon wrote that "Poor" is a difficult term to define and "often means too much." 

The 1793 Flowing Hair, Wreath cent pictured is an example of a Basal State coin even though the date is worn off. As Roach wrote in 2013, "The presence of Liberty’s profile and the edge lettering, along with part of the leaves over the date, allow for specific identification."