If something's unspecified, you don't know the specifics, at least not yet. If your housemate offers to trade this week's dishes for next week's dusting and an unspecified chore to be named later, you should consider this offer carefully.
Unspecified's base word, specify comes from the Latin word specificare, which means "to mention particularly." The prefix un means "not," so unspecified is something that is not particularly mentioned. If you've been sent to the store for an unspecified fruit, you might as well get your favorite. Are apples really your favorite?
