Why is the ninth month called September?
late 14c., "fact of being useful," from Old French utilite "usefulness" (late 13c.), earlier utilitet (12c.), from Latin utilitatem (nominative utilitas) "usefulness, serviceableness, profit," from utilis "usable," from uti (see use (v.)). As a shortened form of public utility it is recorded from 1930.
in economics, the determination of the prices of goods and services.