I don't know, in my experience a "date" just means a time set aside to meet with someone to do something. For example "I have a lunch date with two of my good girlfriends today." Or "I have a dinner date tonight with a new beau." One is just friendly, one is perhaps more.
According to dictionary.com -- date (noun):
1.a particular month, day, and year at which some event happened or will happen: July 4, 1776 was the date of the signing of the Declaration of Independence.
2. the day of the month: Is today's date the 7th or the 8th?
3. an inscription on a writing, coin, etc., that shows the time, or time and place, of writing, casting, delivery, etc.: a letter bearing the date January 16.
4. the time or period to which any event or thing belongs; period in general: at a late date.
5. the time during which anything lasts; duration: The pity is that childhood has so short a date.
6. an appointment for a particular time: They have a date with their accountant at ten o'clock.
7. a social appointment, engagement, or occasion arranged beforehand with another person: to go out on a date on Saturday night.
8. a person with whom one has such a social appointment or engagement: Can I bring a date to the party?
9. an engagement for an entertainer to perform.
10. dates, the birth and death dates, usually in years, of a person: Dante's dates are 1265 to 1321.
The bolded definitions are the only ones referring to going out with somebody and neither of them implies any specific "seriousness", or anything else other than meeting up with somebody at a certain time to do something.
Date as a verb:
11. to have or bear a date: The letter dates from 1873.
12. to belong to a particular period; have its origin: That dress dates from the 19th century. The architecture dates as far back as 1830.
13. to reckon from some point in time: The custom dates from the days when women wore longer skirts.
14. to go out socially on dates: She dated a lot during high school.
verb (used with object)
15. to mark or furnish with a date: Please date the check as of today.
16. to ascertain or fix the period or point in time of; assign a period or point in time to: The archaeologist dated the ruins as belonging to the early Minoan period.
17. to show the age of; show to be old-fashioned.
18. to make a date with; go out on dates with: He's been dating his best friend's sister.
Again, no particular guidelines as to how serious or longlasting something must be in order to be considered dating. Just, going out with someone to do something.
I think any other meaning attached to dating is highly individualistic and a personal opinion and subjective.
Which basically means we all have different ideas of what dating means, and none of them are the "right" meaning. So it behooves us to be very very clear with people what WE mean by dating, and not make assumptions.
My husband tried to tell me he "doesn't date", and his GF had the same opinion of herself. My opinion "You go out together and do things, eat dinner, talk, have a drink, etc. That's a date."