When two people go out as friends, but one or both parties harbour feelings for the other. Such meetings are used to gauge one's feelings for the other, and usually precede the first date.
William likes Kate. William and Kate regularly meet up as friends and both enjoy each other's company. William slowly develops feelings for Kate. These meetings are known as "pre-dates" and this period is known as "pre-dating".
After which, William and/or Kate propose to go on their first date.
Not quite a date, where you go out with a person you might be interested in dating and they're totally interested (or vice versa), that you've previously met during an activity where you maybe weren't yourself (e.g. a waitress from a bar where you were totally hammered). A pre-date will normally occur at a location of one of the parties choice (generally the less interested one) where there are other people they know close by, in case the other person turns out to be a psycho (e.g. a serial rapist or axe murderer). First date activities can still happen on a pre-date (e.g. flirting, makeout, OTPHJ, etc.), but the date definitely does not count in any running total and will leave at least one of the parties clueless and looking forward to/nervous for the actual first date.
Andrew was really excited for his first date with An, until he found out the location was where her brotherworked, making it a pre-date.
Two people go out on a what seems like a date but nothing occurs after the nights events. The time between the pre-date date and the actual date can be any amount of time but must be after a whole 24 hours. The male on the date doesn't necessarily have to pay.
A man and a woman who have know each other for quite sometime run into each other at a coffee shop and they decide to sit together. They talk about deeper things instead of small talk. Then they go their separate both knowing that something more will occur. This is a pre-date date.
When person A takes a person of interest (person B) out to lunch but does not pay. Person B does not know it is a pre-date and is for person A to evaluate whether they would like to go on a date with the person. Each person pays for their own meal.
I am taking Sally to Spring Roll on a pre-date to see if I would like to date her.