The chimera (キマイラ) was a creature from Greek mythology with a lion's front body, a goat's back body, and a snake for a tail. In modern use chimera can refer to any similar "jigsaw puzzle" creature with body parts from multiple sources.
Chimera in Touhou
Chimeras are usually created artificially by combining two or more animals into one, but natural-born specimens are not unknown. In either case, most chimeras have a dramatically shortened lifespan.