Sentence:  This , plus the habit of many schools of simply <WSD>adding</WSD> interior design to the many subjects of their home economics department , yet , nevertheless , claiming that they teach interior design , has contributed to the low repute of many university courses in interior design . 
Meaning of the word marked with <WSD> tags:  make an addition (to); join or combine or unite with others; increase the quality, quantity, size or scope of