1) Dietary mineral 2) Salt 
== Chemistry == Pyrophosphates were originally prepared by heating phosphates (pyro from the Greek, meaning `fire`). Pyrophosphates generally exhibit the highest solubilities among the phosphates; moreover, they are good complexing agents for metal ions (such as calcium and many transition metals) and have many uses in industrial chemistry. Pyro.....
• (n.) A salt of pyrophosphoric acid.
(from the article `metabolism`) ...catalyze the linkage of fatty acids with CoASH to form a compound that can be called a fatty acyl coenzyme A [21]. This step requires ATP, which ... ...The total energy released from ATP, for example, is usually much greater than is needed for a particular biosynthetic step; thus, many of the ... .....
inhibitors of mineralisation, they may offer up phospate ions in the presence of alkaline phosphatase. Crystals of calcium pyrophosphates are found in abnormal calcification of soft tissue, such as the disc of the TM Joint.
(pi″ro-fos´fāt) any salt of pyrophosphoric acid.
Pyr'o·phos'phate noun (Chemistry) A salt of pyrophosphoric acid. 
(PP, PPi) Type: Term Pronunciation: pī-rō-fos′fāt Definitions: 1. A salt of pyrophosphoric acid; accumulates in cases of hypophosphatasia; sometimes referred to as inorganic pyrophosphate (PPi). Synonyms: diphosphate
[n] - a salt or ester of pyrophosphoric acid
two connected phosphate groups in solution
noun a salt or ester of pyrophosphoric acid
a salt or ester of pyrophosphoric acid.