1) Retrotransposons are transposable DNA elements (transposons) that employ retroviral-like reverse transcription during the process of transposition: retrotransposon DNA is first transcribed into an RNA template, then reverse transcribed into DNA, and then inserted into a new genomic site.

2) A transposable element that undergoes transposition from one place to another in the genome of a cell by forming an intermediate RNA transcript from which a copy of the DNA of the transposable element is made using a reverse transcriptase and inserted into the genome at a new location -- called also retroposon.