a. [ Penta- + acid. ] (Chem.) Capable of neutralizing, or combining with, five molecules of a monobasic acid; having five hydrogen atoms capable of substitution by acid residues; -- said of certain complex bases. [ 1913 Webster ]

n. [ Gr. pe`nte five. ] A five-pointed star, also called a pentagram or pentalpha. See illustr. under pentalpha. Sometimes referring to a similar figure, such as the figure composed of two equilateral triangles intersecting so as to form a six-pointed star. It was used in early ornamental art, and also with superstitious import by the astrologers and mystics of the Middle Ages. The six-pointed star is more comonly called a hexagram, or called Solomon's seal; it resembles the star of David (Magen David) [ 1913 Webster + PJC ]

n. [ Gr. pe`nte five. ] A five-pointed star, also called a pentagram or pentalpha. See illustr. under pentalpha. Sometimes referring to a similar figure, such as the figure composed of two equilateral triangles intersecting so as to form a six-pointed star. It was used in early ornamental art, and also with superstitious import by the astrologers and mystics of the Middle Ages. The six-pointed star is more comonly called a hexagram, or called Solomon's seal; it resembles the star of David (Magen David) [ 1913 Webster + PJC ]