Definition
SCHEDULED TIME OF ARRIVAL (STA)
A STA is the desired time that an aircraft should cross a certain point (landing or metering fix). It takes other traffic and airspace configuration into account. A STA time shows the results of the TBFM scheduler that has calculated an arrival time according to parameters such as optimized spacing, aircraft performance, and weather.
Source: FAA Pilot/Controller Glossary (verbatim from the Federal Aviation Regulations).