A warlock was the male equivalent of a Sorceress. A warlock is more commonly known as a Wizard but he is not a Sorcerer. A warlock (or wizard) is to a Sorcerer as water is to oil; this can be used to easily grasp how they are different:
Sorcerers and warlocks are immune to each other's magic-their magic cannot combine in any way (like water and oil), but their magic can be used to do generally the same things (unlike water and oil).
Warlocks are also far more powerful than Sorceresses because the male gift is stronger than the female, like most of the muscles on a regular human body. Warlocks can vary in strength in their gift, or not even have the gift at all. A person is proclaimed a Warlock when he can manipulate his Han, either through being Gifted or through the The Calling. Warlocks manipulate their Han to change, move, or add onto the world around them, although this is only the plus side of things; the minus side of the Han is the ability to destroy matter, undo what has been done, and to take away from what is already there.
It is also possible that a warlock is the male counterpart of a Witch woman, as Zeddicus Zu'l Zorander remarks, albeit sarcastically, that "Girls are witches, boys are called warlocks". It is not known whether he was being serious or not, however.