Also known as the Pearson product-moment correlation coefficient, the correlation coefficient (r) measures the linear relationship between two variables, with a value range of -1 to 1. A value close to 1 indicates there is a strong positive linear correlation between two variables; that is, when one variable increases so does the other.
A short definition. Delta H of a reaction is the enthalpy of reaction. H of products minus H of reactants. Each compound has a delta H of formation (dHf). The heats of formation for each substance in a reaction can be added together to compute the energy change for a reaction.
What is 'Delta'. Delta is the ratio comparing the change in the price of the underlying asset to the corresponding change in the price of a derivative. For example, if a stock option has a delta value of 0.65, this means that if the underlying stock increases in price by $1, the option will rise by $0.65, all else equal.