In the first two quizzes on antonyms we learnt that antonyms are of three types - graded, complementary and relational. We learnt that graded antonyms are known as such because they do not possess an either-or association but rather a more-less association. We now take a look at complementary antonyms.
The dictionary meaning of complementary is ‘acting as or forming a complement; completing.’ Thus, complementary antonyms have the characteristics of completeness with no grades in between. For instance, the word 'night' and its antonym 'day' come under the category of complementary antonyms. Such words have either one possibility or the other. It cannot be both day and night at the same time! Other such examples are before/after; dead/alive, pass/fail, on/off and true/false. In each of these examples you can see that if one is there the other is not. You either pass an exam or fail an exam. A statement is either true or false. A person can be dead, and if he is not dead then he is alive.