In John Langshaw Austin's philosophy of language and the book Sense and Sensibilia, a trouser-word is a term that is not itself defined in terms of content, but only gains meaning through the contrast to its negation. The negative use "wears the trousers in the relationship."[1] [2] [3] [4]
According to Austin, terms are usually defined by their own criteria. To know what it means that something is X (or is an X), one has to know the criteria for it. Only with this knowledge can one say when something is not X (or not X). With trouser-words, the opposite is true: something is Y if it doesn't meet any of the criteria for not being Y. Typical examples are for Austin real, same, and directly . Only in contrast to e. g. a fake duck, say a toy duck or a picture of a duck, does the predicate real have any meaning in the phrase "a real duck."[5]