Sentence:  It rested its decision solely on 7 , which reads in pertinent part : `` [ N ] o corporation engaged in commerce shall acquire , directly or indirectly , the whole or any part of the stock or other share capital of another corporation engaged also in commerce , where the effect of such acquisition may be to substantially lessen <WSD>competition</WSD> between the corporation whose stock is so acquired and the corporation making the acquisition , or to restrain such commerce in any section or community , or tend to create a monopoly of any line of commerce . 
Meaning of the word marked with <WSD> tags:  a business relation in which two parties compete to gain customers