1. (informal) anything complex, detailed or confusing 
2. The science or study of rockets and their design

Encyclopedia: Rocket science

• cirrus
• cirrus cloud
• Cirsium
• Cirsium arvense
• Cirsium discolor
• Cirsium eriophorum
• Cirsium flodmanii
• Cirsium helenioides
• Cirsium heterophylum
• Cirsium lanceolatum
• Cirsium rivulare
• Cirsium vulgare
• CIS
• cisalpine
• CISC
• cisco
• cislunar
• cismontane
• cissy
• cist
• Cistaceae
• Cistercian
• cistern
• cisterna
• Cistothorus