Sentence:  For <WSD>complementarity</WSD>, there are entailments both from affirmative sentences to the corresponding negative sentences (which is what ordinary antonymy allows) and from negative sentences to the corresponding affirmative sentences. [...] "That light is on" entails "That light is not off". "That light is not on" entails "That light is off". 
Meaning of the word marked with <WSD> tags:  A semantic relationship between two words wherein negative use of one entails the affirmative of the other with no gradability; the relation of binary antonyms.