In horse racing, ‘novice’ is often used in the same sense that it is used elsewhere – that is, to describe a horse that is new to racing, or inexperienced in its selected discipline – but, officially, ‘novice’ has a highly-specific meaning.
Under the Rules of Racing, on the Flat, a novice is any horse that is eligible to run in a novice, novice auction or median auction novice race. What that means, essentially, it that is has won no more than twice and has run no more than twice, unless it has yet to win or is a two-year-old, although it must also satisfy certain other eligibility criteria.
In National Hunt racing, a novice is defined as a horse that has yet to win, in its selected discipline – that is, over hurdles or fences – before the start of the current season. The only caveat is that horses that win one or more races in their selected discipline in the last two months of the National Hunt season ‘proper’ are still regarded as novices, and therefore eligible to run in novice hurdles or novice steeplechases, until the end of the following October.