Chimera (pl. chimaera) 

An organism that contains cells or tissues with a different genotype. These can be mutated cells of the host organism or cells from a different organism or species. (ORNL) (http://bioinfbook.org/appendix.php). For transcriptome assembly, The percentage of chimaeras that occur owing to misassemblies among all of the assembled transcripts. A chimeric transcript is one that contains non-repetitive parts from two or more different reference genes. They can arise from biological sources (gene fusions or trans-splicing), experimental sources (intermolecular ligation) or informatics sources (misassemblies). Misassembled chimeric transcripts can be distinguished from true chimaeras by determining whether the number of reads spanning the chimeric junction is significant when compared to the number of reads spanning other segments of the transcript. (Martin 2011)