Mathematical exponents

• Signs I’d since altered
• Dow Jones stats
• Textbook adjuncts
• Scales of charges Spain introduced for third of Catalans

WordNet Word definitions in WordNet
n. a numerical scale used to compare variables with one another or with some reference number a number or ratio (a value on a scale of measurement) derived from a series of observed facts; can reveal relative changes as a function of time [syn: index number ...

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Index \In"dex\, n.; pl. E. Indexes , L. Indices (?). [L.: cf. F. index. See Indicate , Diction .] That which points out; that which shows, indicates, manifests, or discloses; as, the increasing unemployment rate is an index of how much the economy has slowed. ...

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
according to OED, the plural form of index preferable in scientific and mathematical senses of that word.