Usage Note: The –tween in between comes from the same Indo-European root that gave us two, twain, and duo, and the –mong of among comes from an Old English word that meant "crowd" or "throng." It is thus unsurprising that a traditional rule requires between to be used only for sentences involving two items and among for sentences involving more than two. Indeed, in sentences involving two items, no rule is needed; native English speakers spontaneously use between (as in the differences between [not among] karate and judo). But when there are more than two items, practice is mixed. Many careful writers observe a more subtle distinction, using among when the sentence refers to the entities collectively or as a mass, as in There were many outstanding players among the teams in the quarterfinal round or A thistle is growing among the roses, but preferring between when the sentence refers to relationships involving particular pairs of entities from within the group, as in We haven't yet assigned the matchups between teams in the quarterfinal round or I have sand between my toes. In such sentences, the twoness of between has not, so to speak, been lost in the crowd—the pairings within the larger group are important to the meaning of the sentence and thus influence the writer's choice of preposition.