duplication UK /djuː.plɪˈkeɪ.ʃən/US /d(j)u.plɪˈkeɪ.ʃən/ noun6 •The act of duplicating.Another argument for closing Woodhead was simply one of route duplication, and this was the main reason put forward by BR at the time. — 2021 •The act of copying a nucleotide sequence from one chromosome to another. •A duplicate.Registration of trademarks had been revised and a unit had been set up to clear up duplications. — 1949 •A nucleotide sequence copied through such a process. •The act or process of dividing by natural growth or spontaneous action.duplication of cartilage cells •A folding over; a fold. formsduplications