|an initial advantage in a competitive situation|
|[originally referring to a horse's having its head in front of others at the start of a race]|
An early start that confers an advantage, as in This year we'll get a head start on the competition by running more ads. The expression comes from racing, where it was used for a horse being given an advantage of several lengths over the others. Its extension to other areas dates from the early 1900s.