Wikipedia
A semi-feral animal is an animal that lives predominantly in a feral state, but has some contact and experience with humans. This may be due to having been born into a domesticated state and then reverting to life in wild conditions, or it may be an animal that grows up in essentially wild conditions but has developed a comfort level with humans due to feeding, receiving medical care, or similar contacts.
Definitions of semi-feral in relation to cats vary, but essentially describe an originally domesticated cat that has reverted to the wild and is no longer owned or kept by someone. Semi-feral cats may continue to live in proximity to humans and may be accustomed to their presence. Feral cats on the other hand are generally agreed to be the descendants of domesticated cats that have themselves never been domesticated. A semi-feral cat that mates and gives birth to a litter will produce feral offspring.
In the context of horses and horse breeds, semi-feral animals are those which are often untrained but usually owned by individuals. They are allowed to run in a natural state approaching that of wild conditions, but are periodically rounded up for assorted reasons, such as to wean foals, administer routine or emergency veterinary care, and so on. An example is the Camargue horse of France. Truly feral horses, such as the American Mustang or Australian Brumby have domesticated ancestors, but generally have no human ownership and live in essentially wild conditions, though they may also occasionally be rounded up for various management purposes. A true wild horse can only be a horse without any domesticated ancestors. The only living, truly wild horse is the Przewalski's horse.
Usage examples of "semi-feral".
Whole sections had been taken over by the King’s pack of semi-feral spaniels, who’d become inbred even by Royal standards and thus hare-brained even by Spaniel standards.