Pen`ta*ba"sic (?), a. [Penta- + basic.] (Chem.) Capable of uniting with five molecules of a monacid base; having five acid hydrogen atoms capable of substitution by a basic radical; -- said of certain acids.

• (chemistry) (of an acid) containing five replaceable hydrogen atoms
  
• (chemistry) (of a salt) having five atoms of a univalent metal