A "foot fault" is an infraction in sports such as tennis or volleyball where a player steps over the line or onto the court before serving the ball. However, there are several synonyms for "foot fault" that can be used in different contexts. For example, "violation of service" or "service error" are often used interchangeably to describe the same infraction in sports. "Offside" is another term that is sometimes used to refer to a foot fault, particularly in soccer or American football. Other synonyms for "foot fault" include "line violation," "foot foul," or simply "fault." Ultimately, the specific terminology used may vary depending on the sport or the context in which it is used.