A person who is interested in going out on a date with you at a specific time and place but expects you to cancel whatever plans or commitments you had that on that day in order to it. If the person is unwilling to cancel their other plans/commitments, the dater then loses interest in the person and moves on to another guy/girl. Commonly found on online dating websites.
Girl: Wanna go out sometime?
Guy: Sure, When are you free ?
Girl: I'm free on Monday.
Guy: I have class on Mondays. Can we go out on another day?
Girl: Doesn't sound like you're interested in going out with me. Gotta go.
Guy: Yes I do can't we go another time....Hello ? That girl is such an ultimatum dater.
by CapAIM November 2, 2009
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