High/low, yes/no, black/white. There's something reassuring about opposites. A lot of vocabulary teaching is done using pairs of opposites, and with good reason: learners really feel they have a handle on a concept if they grasp its antithesis. There are, however, some other concept families that are best learned using three terms — triples — that provide a middle ground which in turn enhances all three concepts.

The term "middle ground" can sometimes be seen as a muddle, a wishy washy complication. In this case however, the middle term strengthens the extremes and clarifies the entire group. Take colors as an analogy. If you're asked to identify shades of red, for example, having the concept of "pink" established serves to make the members of the category "light red" even redder because the really light shades fall into a different category altogether. So it is with these triples.

Take for instance {uninterested, disinterested, and interested}. The difference between uninterested and disinterested has all but collapsed in modern usage and many people use the two interchangeably to mean "not interested." Restoring the original meaning of a neutral term like disinterested, "unaffected by self interest," rejuvenates uninterested, "not having or showing interest," turning it into an active lack or refusal rather than mere impartiality.

Having three terms opens up shades of meaning that can otherwise be lost in a pair. The most famous triple may be {immoral, amoral, and moral}. Amoral and immoral are often taught as a pair because they can be confused for one another, but by teaching the three words as a group, immoral and moral get to be the pair of opposites while amoral, the third term, is freed up to be the neutral term, true to its meaning. How the words interact with each other introduces nuances, and because the student is only learning one more word, it is not an overwhelming lesson. On its own, rejection is pretty bad, but feeling dejected or to be in "abject despair" can put mere rejection in context, and make it not so bad after all. When presented with a fuller range of other options, a student can begin to see where a word they thought they knew fits in to the larger whole.

Some triples are perhaps best thought of not as two extreme poles and a middle, but as steps in a process towards an end point. You can see {adhere, cohere, and inhere} as a journey to full incorporation: from "sticking to," to "hanging together," to "being an essential part of." This is an especially vivid grouping, easily visualized with two one-celled organism perhaps, who start out as separate entities but ultimately undergo a process where one is absorbed into the other, until no trace of their origin as distinct creatures remains. Here the middle term, in this case cohere, "come or be in close contact with; stick or hold together come or be in close contact with; stick or hold together," is important because it functions as a kind of base camp before the final ascent — it tells you where you have been and foretells where you are going.

Triples can also help clear up notoriously difficult distinctions between terms. {Emigrate, immigrate, migrate} is, like {adhere, cohere, inhere}, a triple that benefits from some visualization, with emigrate emphasizing the leaving of one's country and immigrate emphasizing the entering of a new country with the intention of permanent residence. For more on this triple, see Vocabulary.com's Choose Your Words article.

If we refer to {few, several and some} as a triple, the first two can be seen as the positive and negative component of the third. That is, few has a negative connotation (here it is distinguished from "a few" : "Few people came to my party" is quite sad , but "a few people came to my party" is at least looking on the bright side.) Several is a positive assertion ( this isn't to say that several is always positive: "Several weasels are gnawing on my knuckles" is not a positive sentence, but it doesn't focus on the paucity of the weasel population the way the same sentence with few would.) Some can be either positive or negative. It is as if few and several have combined parts of their meanings to make some.

The introduction of triples as opposed to pairs is really the beginning of contextualization. It is the next important step in distinguishing variation in meaning beyond binary opposition and an easy way to get students to learn the value of being specific. Specificity is a crucial part of good writing of any sort and teaching words as sets of triples can be a painless way to motivate students to recognize the gray between the black and the white.