secretliker SG In the following examples, it would cause an awkward construction of a noun beside a noun.Mountain Bike = Bikes that can be used on mountainsPaper Towel = Towel that is made from paperSchool Student = Student from a schoolThus is it grammatical to use a noun as an adjective?I did research and what I gathered. http://www.englishclub.com/grammar/nouns-group-adjective.htm http://www.english-zone.com/grammar/adjective3.html http://www.rhlschool.com/eng8n1.htm http://www.usingenglish.com/glossary/noun-as-adjective.html